The original is the original I guess, it remains in our hearts and minds and is hard to deviate from. Even the Monkey Island remakes were only slightly interesting to me, I would play the originals if I ever wanted MI or MI2 again.
A new game is always better. The most I want for old games is an HD re-release on consoles.
My girlfriend loves Monkey Island, but there is no way she would ever contemplate playing the original version. It's the same for a friend at work, who had never played MI before I gave sent him the games on Steam.
Personally I like re-makes, and I would love it if my favourite RPGs could be re-released. Especially if they could include some extra content (and even add-ons).
I have, however, more or less given up on point-and-click adventures. The last one I truly liked was Day of the Tentacle (which is also my all time favourite adventure game), and that's the main reason I've contributed to the Double Fine Adventure. I don't expect the game to be for me, but at least I think my girlfriend will like it.