Hmmm. I keep waffling on this. On the one hand, we already have 5 combat stats, due to the three mental stats each being what's used for certain schools of magic, so it's not like it's a sudden increase in complexity. And while there's a placeholder for psionics, there's no actual psionics in play yet (UA notwithstanding), so it's more like four slots.
While I wouldn't mind simplifying, I don't think it would be useful to simplify them at this stage of development. They feel like they cover broad enough topics that are easy enough to grasp that there shouldn't be an issue associating each type with each stat. It even feels simpler than the existing system in some ways. (EG: You can use a dagger using Dex, unless you want to use Str. You use Int for magic, unless you're using Wis for magic, or maybe Cha for magic. No, your Str doesn't help you use a longbow. Etc, etc.)
In addition to what Kyutaru said, also consider that the sorcerer won't have proficiency in using a sword (never mind things like multiattack), so won't be nearly as good at it. Just because he's buff enough to swing a sword around a little doesn't suddenly make him a melee fighter. There's plenty of room to handle the roleplaying differences in there.