Gambling is fair provided the odds are even, but the odds almost never are and there are other factors in play in regards to fighting games such as knowledge and reaction time which have nothing to do with odds. As much as possible, players would prefer they are allowed to choose options that decide their own odds of success and payout.
As far as stages go, I've always been in favor of revamping how we do stages in tournament play. Community decides on several neutral stages to start with that get put on the random filter for the first match, then the loser picks the next stage. Fair.