Actually you are right, a lot of these games would be quite difficult to remake in the same style or even perspective.
It's why Fallout 3 is 3D now, not 2D isometric. But it inevitably makes it a different game altogether.
I guess nostalgia alone just isn't enough to relive these great experiences as remakes, but some remakes are very worthy interpretations of the originals,
edit:
Will do!
Cheers