By making it optional it would be a win-win situation for both sides. The steam camp can enjoy the all the benifits of using steam and non-steam users don't have to worry about any of the other issues raised.
If other games are functioning successfully in both steam and non-steam modes why is there such a big push to assimulate everyone into the collective?
Edit- How about an poll option - I don't mind steam but I would not be able to use the software purchaced in the manner that I wish without viloating the terms of the agreement?
Cheers!