The problem is that, while that's truth, you can't control what stats go up and what stats go up. Depending on your sets your chances of getting an useful stat boost can be 1/7, 2/7 or perhaps 3/7, but even then in the avarage, the inconsistent user will lose.
Same applies to stat drops.
Personally, I like go gamble and I believe Pokemon is a good gambling game, so I don't mind inconsistent. I use it but also I've never been sweeped when others used it against me, but again, I've witnessed so many hate towards Inconsistent, it goes beyond any normal thinking.
In any case, nobody can't deny it has counters, neither that it's based on luck. I think the "based on luck" thing it's what makes it banned (not necessarily broken), but I don't mind luck.