I'll take it point by point and give a response a shot.
OH/Mixup stuff- almost no character has these. Liu Kang doesn't. Nor Skarlet, Noob, Cassie, Baraka, and Kung Lao.
Characters that do have "mixups" like Kabal are almost all unsafe and don't lead to a full combo reward. Sub Zero is an exception to this, not the rule, and it's why he's top tier right now. Jade and Skarlet have seeable overheads. Raiden's is unseeable, but doesn't lead to any followup and is full combo punishable on block. Almost no one has mixups, you're safe blocking low against almost everyone and standing blocking overheads on reaction.
High strings are another universal issue right now. If you explore the rest of the cast, you'll find that almost every character functions this way. Almost everyone's best moves are highs. The reason this isn't too bad an issue is because of things like of Johnny's god tier d4 jailing into his f3 on hit, and ji2 jailing into highs. You can look for jump ins on wakeup and try to mess with the spacing for jump kick instead into dash f4 nutpunch once they start anti-airing you.
His projectiles being high is a necessary trade off since they have some of the best frame data in the game. The only projectile with better frames is Sonya's. And although the 2nd forceball is high, both forceballs jail on block- which is not something everyone gets. Neither Liu Kang's high or low fireballs jail. Not only do they jail off block strings, they are + and do great chip. So if someone is low poking you out, f4 into amped forceballs is a great way to begin pressure and look for whiff punishes.
Special moves- this isn't specific to Johnny. Safe specials without startup gaps are other flaws are RARE. And we have a safe special in forceballs that we can go into out of any blockstring. This isn't an issue.
Damage output, Johnny's up there in mid tier for this category in what he can get for 1 and 2 bars. Again, explore the cast more. before arguing this.
KB's suck. Hopefully we get requirements changed for them.
What we need is high hitboxes to be fixed so they don't whiff crouch blockers. If your forceballs get ducked on block out of f4 or b34 or something, you know it's a matchup you just can't play Johnny into until it's fixed. Basically it. Explore the cast, I can't say it enough. I tried messing with Kabal. He's got ranged mids, so he must be awesome, right? Then you realize how valuable Johnny's walk and dash speed is, because Kabal's is straight ass! Try playing with forceballs in mid range more, rather than fullscreen. It's one of the safest projectiles in the entire game, so it makes a great whiff punish/shimmy tool if you're afraid they'll outrange you. One last strength I'll mention is his restand is amazing. As far as I know, no one in the game has a restand better than +5. Kabals is +3, Skarlet's is +4 amped, and Noob has a +5, but it leaves him far enough that he has to dash before he can grab. Using nutpunch as an ender doesn't seem like much, but you take ALL their wakeup choices and guarantee a mixup between throw and d1 (or d4 for block pushback). D1 beats anything they do besides blocking. It nets a conversion if they try to jump out, it nets + frames if they neutral crouch or mash. And then you've got your throws.
There's my best bet to address your points... Lotta fucking typing today. Fingers dying.
Subzero, Sonya, Scorpion, Erron Black all have true mixup potential. In comparison to a character like, Johnny. We can try and rationalize it with how negative these mixups are, but the meta has been established early and it's obvious why these characters are so high on the tier list at the moment. Of course it should be unsafe mixups, but just that threat alone, takes so much away from other characters that are playing in an honest setting. You can't have balance like that. IMO
The only other character that is top tier that doesn't have a strong mixup game is, Gerras. He's so strong because he has so many mids it's laughable, safe strings, and a means to keep you frozen in air without breaking out.
Otherwise, everyone else is just kinda hanging out. If you eliminated those five characters, it would be a lot more balanced.
Jailing is great but it also has limitations as well, we all know this, and doesn't change the current meta.
I would rather have a mid projectile (amp'd) than the faster recovery or jailed double hit. You just can't establish it properly against anyone that knows what they are doing. Duck, walk forward, Duck, walk forward. Now, I understand this is typical means of countering zoning, I also understand Johnny is not a pure zoner, however, without a threat of that Mid, it's just useless and does nothing but eat clock off the timer.
I'm not complaining about the special moves, other than, there are a few characters that have safe specials that just seem absurd if you think about it. Again, my issue is balance, not the negative aspect of this.
I have explored the cast more. Noob, Gerras, Kabal, Sonya, etc.. I could keep going, but I wont. They all have fairly easier execution strings, with far more potency and damage behind their combo's.
Again, my argument is about the balance, if you had an equal playing field with all characters, they gameplay would be so much more enjoyable. That's my argument. Johnny does not fit the current meta, in a few different ways. If you want a game with trade off, then make the trade off worth while to maintain that balance. You just don't get that with Johnny right now.
Again, I love the way Johnny plays, I understand a good amount about fighting games. I just don't think he fits right now, but, I also think he should be the standard for other characters moving forward. If that makes sense.
I agree that KB needs a rework already and Hitbox and Hurtbox issues need adjusted.
I do use the restand a lot, I only cash out on DMG to close out rounds typically. Thanks for your input and thought out response. I do appreciate it overall. You make some valid points, I just hope that I provided good reasoning on my counter points.
Thanks again.