In all honesty, I see the appeal of these groups. Sited allows a private forum for discussion, so not everyone has to be on at the same time. Mapped is private and can be made your own, as barren of a wasteland as you'd like or a little city. I have no problem with these at all. I do prefer literate roleplays myself, simply because it's more pleasing than one line replies and purposefully lazy grammar.
However, it is very nice to be able to relax or multitask while roleplaying rather than putting all of my time into it, in my personal opinion. The only thing that really rubs me the wrong way is that some of these groups don't allow roleplay newbies, not giving them an environment to learn and grow as a storyteller. Of course, this generally has to do with their preferences rather than a personal dislike for the newbie.
Overall, people can do what they want. I just wish some groups were a bit less intimidating, is all. <3