A game needs rules for things the game expects the players to do a lot of.
Additionally, a game does not need rules unless it's resolving a conflict, so all rules need to be conflict resolution tools first and foremost.
A good DM is a substitute for any rules on all occasions. A good DM can run FATAL and make it a great game. A good DM should not be a prerequisite for play. Normal DMs should also be able to play.
D&D has never generally expected players to do "a lot of" social stuff, but it's always had some "social powers," either through things like NWPs and skills, or through spells like
Charm Person. These help resolve social conflicts, convincing NPC's of things.
D&D has usually had a LOT of Exploration stuff. NWPs and Skills again, but also a boatload of spells like
Fly,
Teleport,
Scrying,
Water Breathing, etc. In most editions, these exploration tools wound up being the most powerful things in the game (the ol' scry-buff-teleport relies on them!). These help resolve environmental conflicts, getting from Point A to Point B with the least amount of attrition (and, also in this category, Investigation stuff that resolves conflicts of exposing information to the party).
4e mostly killed these two avenues, because rituals and skill challenges are weak sauce for people who want to do a lot of social stuff or exploration stuff. Skill challenges lack depth, uniqueness, and diversity, while rituals are high-level, narrow use, expensive, and risky.
They are the seeds of good ideas, of course. Rituals are a great way to silo combat magic from noncombat magic, they just
need to be accounted differently and expanded. Skill Challenges are the core of a great "lite combat" system that can be used for a variety of challenges, they just need
more detail and individuality. And the whole system needs to
zoom out a bit from combat so that those conflicts are relevant to the gameplay, rather than just condiments on our combat burger (warburger?).
Oh, and the game needs to be, like, 10 levels instead of 30. But that's a pacing/marketing decision.
