I made no value judgement except to point out that Gary's prescribed style was the grandfather of dungeon crasher games, Gauntlet being the most famous. But if you want, I'll state that the idea of D&D being best played as excursions into a dungeon for the only purpose is to get treasure (which is XP, which gains you levels, which allows you go further into the dungeon) IS a simplistic form of D&D and ignores all manner of alternative styles of play (wilderness/hex crawl, story first/immersive, adventure path, etc).
My point is that that dungeon crawl isn't any better just because it was Gary's preferred method, and the game branched out from that as the only/preferred method rather quickly.
Also, I like Gauntlet. It's a fun game. But I also like Final Fantasy and Legend of Zelda. D&D can do L of those.