Back to fifth.....
I actually like that the levelling system gets you more optimized for "stuff". Not super optimized, just in a general direction.
"Here, have some stats. You're way better at some things now. Well, umm, like a tiny bit better. But those things don't get too hard usually. Plus you're sometimes better at heaps of stuff. Or heaps better at specific stuff. You can multi-class, but you don't have to. You'll still be pretty good at some stuff. You DID make sure you optimized, didn't you? Oh well, shit happens. Theatre of the mind and all that. I hope you can roleplay or think a bit. Otherwise you're really fucked."
Note: This is a lot better than 2nd, 3rd, 3.5, or probably even 4th (which should be an awesome turn-based computer game).
5th's kind of nice. Any class can do a bit of "stuff". Different pathways for everyone at third level at the latest. Spells if you want them. Multi-class if you want. But you often don't have to so that you can contribute.
Munchkin away, but honestly not necessary. Hell, I post on min/max boards. There's enough fluff in 5th that even when going for a very narrow build that is specifically good at something, you've got heaps of stuff to do as well. In the core rules, no splat-books. So has every other vaguely coherent character, statted or RP'd. 'Tis nice.
There's statistically better and worse characters at doing some things, but virtually every character can be roleplayed as a character, not a stat block. The DM can adjust the flow of an adventure to almost any setting or style, because it really is up to the players on what they'll do and how they'll cooperate.
Power Attack no. Walking, talking, thinking or collaboration for adventure? Yeah. It's not perfect, but I tend to think it's the best balance between rules and DM storytelling so far for DnD, with inclusivity of player actions actually meaningful without godlike stat crunching and feat taking.