We're aware she's not real right? xD and she doesn't even come off as remotely sexual. I don't see where you guys are seeing this. Apart from the battlesuit, which isn't really sexual as much as it is a terrible design altogether.... her moveset, her win poses, her everything is far from sexual. So if she was "14" the only reason it would be frowned upon is because you can beat up on her.
I just think it's hilarious however, that everyone is against the idea that she 'does' look like some girls who are over the age of 18... have you seen Japan? girls look 12 well into their 20's. This really isn't anything unusual.
Look at Lili in Tekken, she is younger than Marie Rose, yet she looks older than Asuka. Then there is Xiaoyu, who is older than Asuka, and Lili, but she looks like she's 14/15- but she's apparently 19. The only reason this is seemingly producing a lot of heat is because the game is DOA. It'd be perfectly fine if she was thrown into VF, Tekken, SC, KoF, SF or any other fighter for that matter, but because it's DOA, let's hate on the idea. Which goes to show you how people, even within the community view the game.
In SC and Tekken you can actually dress the girls in practically nothing thanks to customization, not to mention SC where you could literally strip off everything but a tiny piece of cloth covering the private areas.... Marie Rose is really nothing in comparison to those. In which the games characters were literally under-age.