The bad motives that dems could have is that they would lose the vote of illegals. I am sure you know how both parties send out buses to pick up people to vote. I don't see what would stop them from hustling up some illegals to support the cause, and there is nothing very "conspiracy theory" about this notion either. It is about getting every single vote that one can get, be it one more vote or 40 more votes.What bad motives can be ascribed to Dems in this whole fracas?
Reasonable ones, that is... not some grand conspiracy theory about legal & illegal aliens voting Democratic in droves.
If strict voter ID were obviously important and necessary, then we'd have a lot more evidence that such is the case rather than mere belief... proponents would be able to cite significant fraud, not a few edge cases. Not to mention that if good ideas have bad motivations, they're few & far between, entirely accidental, the result of unintended consequences.
Hypothetically, If there was a way to ensure that poor voters could get their photo IDs, would you still be against requiring photo ID?