I agree that Track, Open Locks, Disarm Traps and Pick Pockets shouldn't be feats. (and Open Locks/Disarm Traps should be the same skill).
For Open Locks/Disarm Traps, though, that brings back the issue of Thieves' Tools proficiencies, which needs to be solved in a different way. Also, because they are ability rolls not skill rolls, the difference between someone specializing at pocket picking, and someone just trying it out becomes much more marginal. Which is to say: There is at least a reason behind the choices they've made, even if problems remain.