Prior to then enhc pass it was announced each race would have pres, halfling acrobat, drow tempest etc etc.
For whatever reason they abandoned these except for elven aa.
Pure classed characters would have added versatility and less need to spend ap on the fluff. Multis would get some benefit as well, but would have to sacrifice somewhere due to tighter ap.
For humans, to further build on versatility theme, you could have them choose whichever extra class tree they want(but only one) and only make up to core2/tier2 enhancements available.