I have no issue with any online game, fighters included, by using my wifi connection. It is just more convenient and I don't really notice much of a difference between the two, if at all. Wifi has come a long way over the years afterall.
Now it should be noted that I do not play in tournaments or at a professional capacity, in which case I would want every advantage I can get. But niether do most people, so this percentage is really not surprising at all.