My league has a very similar problem (although my winning hasn't gone on as long and my revenue isn't as high). We plan on introducing a luxury tax in the offseason, but I'm not sure how much it'll affect me.
The problem is on one hand, it gets kinda boring just cruising with a team that good. On the other hand, I always seem to get eliminated from the playoffs, so it can't be THAT good.
The main issue is that although part of me wants to rebuild and start fresh, the common sense part that says not to rebuild a 120 win team that's making a profit takes over. We may possibly restart with the release of V6, so then that would solve the problem anyway.
Sorry to semi-hijack your thread... I just wanted to state that it's not odd for a commish to have a good team. Naturally, there'll be owners in your league who think you're cheating with no actual evidence other than the win-loss record. They usually piss me off. But as long as you're not actually doing anything wrong try not to let it bother you. Just try to do what's best for the league, but don't purposely compromise your team for it.
This is important I feel so it gets its own paragraph. When a commish owns a team ANY DECISION THAT COMBINES THE ROLE OF OWNER/COMMISSIONER SHOULD BE AVOIDED. Most people think of this as cheating by making your team better, and although it's not a normal type of cheating, making your team purposely worse for the benefit of the league still should not be done, as when you're playing the "owner" role, your job is to make the team better. The two roles should not collide.
I'm done. Sorry about all that.