Nerfing save DCs and capping attribute bonuses, without changing monsters and converting SR into save DCs nerfs casters to boring as heck. Also I wouldn't make casters better at damage; that's the whole distinction, casters bf control better/martials do more damage. There are higher level spells with higher dice damage caps; that's fine. Arcane casters shouldn't be about blasting other than when they've already thrown out a few control spells; but taking enemies out of the action is what casters should do, damage should be the province of martials.
Frankly, they need a bit of a nerf. But I'd be capping monster stats as well, just a bit higher, depending on the type of monster and its size.
As far as being better at damage, the spellcaster needs more credible reason to do classic caster things - like cast evocation spells. The hit point bloat of 3e and PF really undermined evocation compared to 1e and 2e. The dice caps made some sense in 2e, but the assumption that led to them was blown away in 3e.
Arcane casters should be about whatever they want to be about and that includes blasting away with flashy magic.