You are selling her short. Mashima is hardly a good writer, but I never felt Wendy was there just to placate lolicons. In my non-lolicon eyes I can't view her as sexy standing next to the likes of Juvia, but I like Wendy as a character because Mashima did manage to give her some childish characteristics. I find it cute how she's just a little girl whereas all the other dragon slayers are gruffy men, yet she's still doing her best in all the fights she's continuously facing as a main character. Furthermore, even on a more basic level I can't help but pity her situation where she has no friends of the same age around but is always in the company of adults (even if some of those adults are almost like kids anyway, like Natsu and Gray). Nah, Fairy Tail wouldn't anymore be Fairy Tail without her.