In the end, I would say that of course it is always preferable to use type correctly, but typography is the servant of meaning, not the master. If straight quotes, however much of a modern bastardisation of type they may seem, enhance the meaning of a piece (or if curved quotes would distract the reader), then you must use them. Otherwise, don’t.
Ministry of Type on March 6th, 2008.
We are still waiting to be shown an example of this supposed enhanced meaning that a prime mark might provide. We’ve also been waiting to see a unicorn.