Heya WilliamF...gotta admit, I don't see the issue here at all. Sure, there have been a ton of discussions about royalties and copyrights and IP protection, etc...but it has been my belief forever that there is no issue with used book stores in any way. Period.
Most used bookstores get a good deal of stuff from people who have already paid for the books originally so the authors have already [hopefully] been compensated. They also probably get overstock books directly from publishers [at a significant discount I would assume] so again, quite up and up.
Unless I am totally off-base [always possible!], you should not for one second feel bad about patronizing used book stores. In fact, I supported a few local NYC used bookshops for many years - they were all run as you say by people who love to read. I found some excellent gems and other hard to find editions at those places. Great great help!
A logical extension of your concept would be that public libraries are conceptually bad, right? And we know that cannot possibly be the case.
Actually, now that I think about it, stores selling used anything are awesome. Music, electronics, musical instruments, clothing, books, whatever and etc...its all good IMO!
my 2cents and cheers,
-les