So just for the sake of argument; I have been thinking about this 'size matters' thread.
Suppose one takes a print that would normally look wonderful at 6x8" size. Say a portrait that you're very pleased with, something subtle and beautiful. If you made this print 5feet by 7feet instead, the relationship with the picture might change and that juxtaposition could be interesting.
There was a thread here a while back about a very large print by Andreas Gursky, Rhein II at 81 x 140 inches in size. It made me wonder how my relationship to one of my own pictures would change if it were printed that large.
While I don't care much for that print by Gursky, size can definitely have an impact on the viewing experience, so it is probably incorrect to state that size isn't an important decision. We can all just decide for ourselves what we like, and I think that perhaps some people are lazy in that regard, and just buy whatever they're supposed to be investing in, or just like what everybody else likes.
I really do think that this discussion is founded in that we should think for ourselves and reach our own conclusions about what we like, and if we care enough it might be interesting to discover why that is too.