Mark Seifter once spitballed an idea for adjusting the math that involved making it so True Strike doesn't work on spell attack spells and then detaching spell attack proficiency from Spell DC.

From there increasing Spell Attack at martial rate for full casters (nobody going Legendary in them) and allowing fundamental runes would be fine in theory (though he hadn't had much testing of it at that point).

This was pre-Psychic which has some things that compensate some varieties for low spell attacks and I haven't tried it with them. However, my group has used this adjustment in several long games and it works just fine. The only issue is if you ever go legendary or encounter balance is off.

If you allow going legendary or there's more higher level enemies than recommended by the rules you'll likely see casters using all their slots on attack buffs and spell attacks because saves will be less consistent. With balanced encounter ratios and non-legendary it works fine though. I wasn't doing as much damage as super high damage classes, but my damage was decent and balanced because you still need to use higher level slots to really keep up. Plus needing to buy an item for item bonus takes away money you could use on a staff or scrolls, which are pretty good things to have and could in some ways be a better investment.

Psychics however can get Emotional Surge though for easy +2 status to accuracy and have access to chunkier spell attack spells than other caster, so it might be problematic there. Haven't tried it.