It says it dropped the "wargame aspect", not the combat system entirely.
So Gary Gygax is simply saying D&D used to be like Warhammer 40k, but instead it dropped that wargame aspect of gameplay and focused on dungeon exploration. Link =
http://en.wikipedia.org/wiki/Editions_o ... 26_Dragons (explaining that the wargame aspect was dropped)
Dungeon exploration occurs in roguelikes and hack and slash games like Diablo and Torchlight. Dungeon exploration doesn't imply no combat. Hell, if there was no combat it wouldn't be dungeon exploration now would it... it would be Amnesia instead.
All those mods are proving is that Grimrock would make a better looking Myst, which was a puzzle-game with no combat.
More likely the esoteric puzzle like strategy was dropped from the game (D&D) in favor of more loot, hack and slash, and dungeon delving.