I think these are pretty big assumptions about play styles (5 minutes to shine, for example). My play sessions are pretty long by most standards (about 10 hours once per week), and we average about one fight per session (three is really spiking for us, and two is high).
Last session, the players spent about two hours in town, going into detail on performing, spending time in the local tavern, and otherwise pursuing in-character interests. To characters with out-of-combat skills, this was not just "5 minutes" of time to shine. Some players (like mine) really enjoy having skills outside of combat, and willingly sacrifice combat ability to pursue those abilities (it's a point-buy game) most of the time (very rarely will you see a purely combat character).
I think they are pretty big assumptions, but in some ways for opposite reasons.
For one, not all DMs can design or ad-lib those types of situations for that long. It's really cool that some can but especially new DMs would probably be really hard-pressed to do so.
I'm also not sure sacrificing combat ability for RP ability is really a viable solution either. The point buy system might work great, but you probably need to have a pool for in-combat and a separate pool for social/rp skills. This then puts us back in the area of what should teh "basic" system be, which is probably decent in combat on equal levels with base skill sets while extended skill sets and combat tactics are separate add-ons.