I think they should make more Halo games only if they want to. I would hate for Halo storyline to be ran down into the ground just because everybody wants a new Halo.
Although a multiplayer only version of Halo could be a way out of it, and I would totally buy it the first day it came out =)
AND I <3 BUNGIE TOO! Which is why I respect their decision and I don't question it, which you all should feel too. Bungie knows what they are doing, and if they feel that it's for the best, than I think it's for the best.