From what I’ve seen – and this is mostly based on personal experience right now, although it could make for an interesting research question – a lot of the deeply felt issues are with RMT that is perceived as cheating (which is one of the things Mia Consalvo deals with in her work). The sentiment seems to be that anything that gives players an advantage through RMT – rather than just being interesting or novel – is more of a threat than more cosmetic items. That said, some criticism of even cosmetic RMT can be seen in-game, but I do wonder how much of that is genuine displeasure versus criticism based on seeing multiples of the same item appearing in-world in general, or even criticism from those who bought a special item and now see many other players in possession of the same commodity.