No, it isn't wrong to voice your opinion. But then again, voicing your opinion with rather extreme and outrageous ideas can be deemed as rather annoying and selfish. Unless you really want someone like me, or the majority of the contradicting society on your case. Joking aside now.
Anyway, (again, something I say repetitively) I think there is the occasional selfish idea in the form of a few threads. Ideas that seem rather ludicrous. If it's something like they should put roller skates in to replace the bike, that can be deemed as selfish, and idiotic. If it's something like a discussion of two item slots, thats ok in my book. It's talking about what could happen and how it could work. However, rather than talking about it, asking whether it should be included is what I'd call selfish. Put simply, threads with ideas are ok, whilst those asking about changing and including aspects in a game are selfish. Still, doesn't mean it's completely ok. In majority, I'd say the threads have a tendency to be selfish opinions.
And, referring to quote, even if it's a what if scenario, that can still make a thread selfish, just like that. Depends on what's being discussed and how it is. Still, this is only my opinion.