The problem is JC, D&D has ALWAYS been a game about combat. That's pretty undeniable. The vast majority of the rules focus on combat and always have. Heck, we went a number of years where the only rules we had were combat oriented. It wasn't until 2e that we started adding more.
So, why are we trying to change what D&D has always fundamentally been about?
We had a poll about that on this site. The majority voted against it being "about combat". Saying it's undeniable doesn't make it true; the majority of people who voted on this site, in fact, deny it (and as this is where the discussion is taking place, it seems fair to use).
And as far as editions go, 2e, 3e, and 4e all tried to branch out. Let's keep that up. Each edition evolves the scope or nature of the game, or tries to. So, why change what D&D is "about"? It's how it usually works.
I don't think that there need be any claim or implication that the game is about combat.
Hussar has explicitly stated as much, and in one post above yours. He also held that position when the poll was posted, and you even disagreed with him in that thread, if I recall.
But I agree with @GreyICE and @Hussar that combat is a fundamental mode of action resolution in D&D.
I do, too. This doesn't mean that forcing people to consistently use combat (or be proficient) is mandatory. People routinely use other abilities to resolve situations; if you can make a purely combat-oriented character (as past editions have done), why not a purely non-combat character? D&D definitely allows non-combat solutions in every edition.
Anyone who thinks that 3E cares as much about musicianship as about swordsmanship needs to explain the anomaly I identify above: that it distinguishes longsword and scimitar proficiency, yet treats skill with the jazz trumpet and skill with classical flute and skill with folk bagpipes as not worth distinguishing.
This isn't what I'm talking about. I'm saying that forced proficiency (in any field) isn't desirable. You can bring your point here up again, but as it's not what I'm discussing, I'll leave out further replies to it.
The game has made clear choices about which distinctions it thinks are worth drawing, and which are not. Having made those choices, the rest of the character build rules should affirm them, not occlude or lie about them.
No need to lie about them. Make it very clear that taking a feat that's not a combat feat makes you worse at combat, and how it will affect your character, your party, and the play style of the game. If people still decide to go with it, then they'll be doing so while informed of what that choice entails. (They should also make it clear what overspecializing leads to, regular specialization, going for a "jack of all trades" feel, etc.)
And then, you know, expand those fields some more. In my RPG, there's really only one completely combat-based skill (Martial Prowess), and it takes up one page. The Skill chapter is 54 pages long (longest chapter in the book), and Combat is 34 pages (which includes 5 pages on mass combat and 12 on martial maneuvers). Then there's another 21 pages later on about handling weather, fire, poisons, drinking, and so on. Then another 17 pages in Chapter 1 for a background generator, status, calling in favors, fame, income, gaining possessions, reputations, etc. Then another 9 pages on crafting items not covered in the book, pricing them, determining DCs, adding features, etc. That's essentially 101 pages vs 34 pages when it comes to combat vs. non-combat (not getting into listed equipment, magic, traits, special abilities, and the like). When it comes to feats, out of the 11 categories of feats, 6 are combat-based, and 5 aren't (though some are useful in combat, and some combat feats are useful out of combat); that chapter is 24 pages long, so with an uneven split of 8 non-combat and 16 combat, the total is still looking like it's 109 non-combat to 50 combat (well, 107 to 52 if you move the Martial Prowess and Tactics skills over).
I'm not saying that non-combat needs to dominate the game, or be anywhere near as long as my stuff, but we can definitely expand upon it in 5e. There's a lot of room to grow.
Then Dungeons and Dragons is not the game for you.
As promised:
http://www.enworld.org/forum/new-ho...76-feats-dont-fail-me-now-feat-design-5e.html. Go ahead and look up the back and forth that I had in this thread to get a feel of my feelings on it (the 3/3/3 default and specialization, optional opt-out of 3/3/3, potential combat and non-combat siloing, etc.).
If you truly want to play a total incompetent at combat, build them! But don't build them in a D&D game.
The option to be bad at combat is bad because...?