Didn't the rules always intrude on the "shared imagination space"? No matter what edition of D&D you play, at some point you're left talking about the mechanics during play (3e all but forces you to play the bonus stacking/adjusting game during what are supposed to be thrilling battles).For someone who's really into the "shared imagined space" of the campaign world, the tactical boardgame is "distracting." And vice versa.
My experience is that RPG's are all about multitasking; they're a chunky blend of different activities. Part tactical war game (I started with 1e and always used map tiles and minis), part collaborative story-telling exercise, part 3-rd rate dinner theater/improv. Sometimes they're ciphers or riddles to solve. I think it's what I like best about RPG's; they several kinds of game at once.