It seems likely enough that some/many people that dislike version X or prefer version Y won't have played version X for long enough to really decide what they like about it. Some will, of course, and on some the realisation of a preference for Y may dawn slowly or incompletely, but if I think about my 4e experience and how I really didn't like the game in practice, I didn't hang around for long enough to admire aspects of it.
However, I have read RMSS pretty thoroughly back in the day and played a small amount, so it's not always that there's nothing there for appreciation; some of it I liked, although abstracting it out of the whole might be hard. However, how I felt about it is pretty coloured by my overall lack of enthusiasm for the game and, at least before RMC came out, there was a clear extent to which ICE had killed off the game I prefer in order to push RMSS. I remember, when RMC did come out and appeared to some/many to be starving RMSS/FRP of oxygen, similar feelings from fans of RMSS/FRP; if they were saying what was good about RM2, they'd arguably be hurting the game they preferred, to some small extent (and similarly for RM2 fans talking about RMSS/FRP). As I can't imagine that new ICE wants to make a commitment to supporting both of them indefinitely going forward* -- particularly with the continuing talk of a revision and bearing in mind that RM2 and RMSS/FRP are pretty different in many key respects -- it seems to me that some people will pretty naturally fight their game's corner because whether the next version looks more like someone's currently favoured version could conceivably be somewhat affected by what people say on the forums, and how persuasive they are.
*I should add, from my perspective, that what ICE have done with RMC and GuildCompanion with RoCo1 is awesome and absent my pie-in-the-sky dreams of at least RoCoII and RoCoIII getting the GC treatment -- I say pie-in-the-sky because as I recall they have many, many authors, all of whom would have to be found and who would all have to give their permission (and who knows how they feel about ICE?) -- a PoD RMC indefinitely available is pretty sweet, even if I'd prefer to see it in distribution again.