Fairy Tail isnt Mashima's first manga. As far as I know, Rave wasn't inspired by Dragon Ball as much as Fairy Tail is. How come Fairy Tails' art is so similar to One Piece, more than Rave was? not to mention designs like Hoteye or whatever his name was, who looks like Kuma.
And I'm aware that Mashima said that his art is similar to One Piece because both he and Oda were inspired by Toriyama.
Well, his art evolved. As an artist myslef, I can say that two years ago, my art was that of a shoujo artist's and completely different from what I draw now. Mostly because I liked shoujo. Then it became more realistic-ish and shounen. Because I like shounen now more than shoujo. You're art develops without your own knowledge; it's a gradual change.
And, well, I haven't read through Rave Master completely, but I have seen the begining art and the ending art. And the begining art is completely different from the ending art, much more similar to Fairy Tail's. And considering how long Rave is, his art must have started changing somewhere in the middle. When he started, his art was very… er, crappy. But as he grew as an artist he learned how to draw things much better and more detailed and etc, and his art reflected that knowledge. You don't just change styles over night, they have to develop on their own. And considering how much free time Mashima has with his work (none) I doubt he was planning to suddenly change styles for a new series. It was a slow change, and just artistic development. Just because it looks similar to one another's art doesn't mean that it was inspired by another's art.
I mean, look at Oda's work. Compare his Romance Dawn stuff with his work now. Completely different styles because his art developed. Same with Fruit's Basket, or Inu Yasha, or Bleach, or FMA, or Clamp. If you draw for a living, you're bound to get better at it, and your style will change.
And, well, I'll be darned if there aren't characters out there that don't look like other anime's characters. Sesshomaru, Ayame and basic bishis for example. And Robin is that cool chick, and every other anime has one. And charas with huge top bulk isn't exactly very rare. Things are bound to look similar to each other, since almost everything in anime has already been done before. Don't read too much into it, it's just coincedence.
Sorry for the essay. Didn't mean to write that much. 8D;