I don't really watch too much now because of these reasons.
1) The judging is extremely questionable. Lennox Lewis was destroying Holyfield and they ended up in a no decision. WHAT? Then I had enough when this happened
http://www.mmatko.com/humberto-soto-vs-francisco-lorenzo-fight-video-fake-injury-boxing/
2) Too many belts. If you got Ruslan Chagaev, Samuel Peter, and Wladamir Klitschko in the same room and asked who the heavyweight world champion is, all three of them would say they were, and they all would be right. No one has all 3 belts in their weight class.
http://sports.yahoo.com/box/leaguepage/champs?prov=st&type=lgns
3) Where are the great fights? We get PPVs for fighter who no one even knows!
4) Too many super fights never happen because boxers dodge fighters or say that the money isn't right. What about being the best?
So in MMA, it is to me more interesting because millions of dollars necessarily hasn't spoiled the boxers too much. We still see huge fights. Once again, I am not a huge MMA fan but I understand it why MMA is catching on while boxing declines.