#you've got stuff like doppio and diavolo (and king crimson?) as an evil system

[idkaguyorsomething]

Is it weird that I am perfectly fine with Araki giving Jodio a severe mental illness but still wish he had given Jodio a different one?

sorry it took so long to answer this one, i was trying to figure out how exactly to answer it, and it turns out there's a lot of different ways:

from a perspective of representation: mental illness is an incredibly stigmatized subject, and in mediums like manga and comic books even more so, as it is incredibly common for a lot of popular plots in those mediums to go "well, x character went crazy, that's why they're evil", as well as stories in general to associate a lack of empathy with a lack of ability to act in traditionally heroic ways. jjba itself has shown that, as part of dio's initial villainous characterization involves him showing a lack of empathy towards various figures such as dario or george (although this isn't the only way his villainy is characterized, as we're also shown right off the bat that he's very deliberately cruel). with jodio being set up as more of an anti-hero, giving him more traits that could be considered unheroic as well as a commonly stigmatized mental disorder, it makes sense to not have that sit quite right. but taking the history of the series into mind, jojo's is no stranger to exploring more shades of gray in its protagonists in its past. johnny and gappy have certainly committed far greater acts of brutality in their parts, while giorno, who jodio is set up as a parallel to, outright aspires to be a head of organized crime. even josuke, who is portrayed as one of the kindest and most pure-of-heart jojos, basically condemns a guy to a fate worse than death in his first arc. this isn't necessarily anything new the series is giving us, and the fact that the jojolands is largely portrayed from the perspective of jodio himself is a massive plus, as it gives us insight into his thought processes and helps us sympathize with a character we might not have done so otherwise (telling a story from the perspective of someone doesn't necessarily ask us to sympathize with them, but things like the goofy jokes he makes with dragona, his own insight on his diagnosis, and his clear love for his family go a long way towards making jodio likeable). one could view this as the natural progression of jojos tending towards the anti-heroic while araki explores more marginalized communities he's interested in portraying, or a poorly thought out decision that furthers stigma towards said marginalized communities. personally, i think it's still too early in the story to make any real judgements, but the way i see it it's kind of similar to the situation with jolyne. she's the only female jojo, and the only one besides jonathan who ultimately fails in her quest at the end of her part. there are narrative and thematic reasons for doing so, but it doesn't sit right with a lot of people, and that's perfectly fine.

from a medical perspective: according to the dsm 5, a person must fit at least three of the criteria for antisocial personality disorder in order to be diagnosed as having it, most of which jodio does fit. failure to conform to social laws and norms (he's a teenage drug dealer), deceitfulness (when barbara ann asks him where he is and if he's hanging out with paco, he lies), impulsivity (he destroys one of the lava rocks to try and get rohan to cooperate), aggressiveness (he kicks that one fucking cop until he's a stain on the ground, twice, although he is justified in his actions and this kind of willingness to fight people is essentially a requirement to be a jojo), reckless disregard of safety (again, practically a requirement for most main characters), consistent irresponsibility (assuming what we've been shown of him is how he acts all the time, yes, although the story so far takes place over too small of a timeframe to determine that), and lack of remorse (dragona has to remind him not to get too violent in the opening chapter with the cop). so he does fit most of the criteria, but it is also a requirement that, to receive a diagnosis, a person must be eighteen or older, with evidence of having fit some of the criteria before the age of fifteen. so by real world standards, jodio would be on track to being diagnosed with antisocial personality disorder, but actually receiving it from a high school psychologist is bullshit. then again, this is the universe where the president made a cowboy race battle royale where the contestants had to collect magic body parts, so it's entirely possible that psychiatric standards in that world are just different. but you would be entirely justified in not liking his diagnosis, and there are several other disorders that fit the behavior that jodio shows. there's adhd (the impulsivity and tendency to get lost in daydreams and beating the shit out of cops), depression (the sense of emptiness he describes upon being given his diagnosis), anxiety (irritability and angry outbursts), and that's just some of the more common disorders. we haven't even gotten into some other full-on personality disorders or common comorbidities with antisocial personality disorder! from this perspective, your assessment is totally fair.

from a thematic perspective: as mentioned earlier, jojo's is no stranger to making its heroes increasingly reflected in shades of gray, and parts seven and eight especially make a point of contrasting their protagonists with their respective foils from parts one and four. johnny is a paraplegic gringo jockey twink that murders people so hard his friend the executioner had to tell him to slow down, in contrast with the jacked and kindly gentleman jonathan who impressed a stranger so much with his dignity that he immediately joined him in his quest. gappy is a quirky lil amnesiac who beats people to death with shovels while josuke has one of the more normal personalities of all the jojos and possibly the lowest kill count. at first it might seem like giorno and jodio are the most similar duo, since they're both criminals that act a-okay with murder, but while giorno's goals and reasoning for joining the criminal underground are motivated by a sense of empathy towards the people of italy and a belief in a higher ideology that passione can aspire to, jodio is a very self-centered kid. he has a very inflated idea of his own reputation, can't spot obvious traps, and the very first thing we're told about him is that he wants to be stinking rich. he also believes in the ideology of mechanisms, but it's an ideology that is explicitly centered around gain and his own material wealth, in contrast to giorno's philosophy, which involves ideals of self-improvement and certain boundaries that should not be crossed in the pursuit of power. giorno's ruthlessness stems from a place of compassion, so having his counterpart being someone who lacks the ability to feel empathy is a really interesting choice that gives the story a lot of places to go. the fact that the other criteria he fills, like impulsiveness and irresponsibility, stand in direct contrast to giorno's ambition and planning ahead, also adds further potential for the jojolands to explore a completely different sort of crime story than golden wind. so from this perspective, i'd say that your assessment is rather harsh.

tl;dr there's a lot of different angles to approach this question from. it's 90% probably that i completely misunderstood what you were trying to ask, though, so please tell me what i got wrong :P