Amongst all this talk of how pointless it is to write these games, there are a few other issues to consider:
1. Fun! I love programming in assembler! To me it is great fun to fix up old games and often end up rewriting buggy parts. I get a lot more enjoyment out of doing something on the Amiga than from making a program/game at work (games using DelphiX). I could redo many old games on the PC very easily but there is no fun in it for me!
2. Nothing beats playing a game with a real joystick on the Amiga! I have thousands of MAME roms and although they are quite fun, I'd prefer to play them on the Amiga with the old style joysticks. However my 50Mhz 030 runs MAME at about 2 frames per second on even the oldest games so they are unplayable. I'm sure there are other people that would like to play some classic games on the Amiga that were never ported (maybe they don't own a decent PC, or have a crappy one or something).
I read a really good website by some coder who also said he liked to program on older systems which had limitations because the fun is in trying to push the machine to it's limits. Having a system that can do everything removed the need for skill or elegance, and I agree totally with that. My former boss was one of the most incompetant programmers I have ever seen yet a fast PC disguised his incompetance to most people. Seeing Sonic running at 50Hz on an Amiga looking like the original would be a great achievement and I hope the project comes to fruition!