Id's history with games has never been about story or plot, it's been about the engine. Never once before have I heard Id use anything other then engine features for their games, and this is another example.
I've been saying it for years and I'll say it again, Id doesn't make games, they make game engines, other companies take it and make games out of it.
And as for the name Doom, it really doesn't do anything for me, Half Life on the other hand does. Will I buy both? I'm sure I will, but I'll buy each for diffrent reasons.