A sport should only be in the Olympics if it is the pinnacle of that sport. Either that or it is the pinnacle of their amateurs i.e. boxing. Having professional football players, basketball players and tennis players at these things take the shine of it.
A sport should also have a clear goal to it and not be judged for me. The true sports have a goal to them, score more runs than this team, score more points than the other team, go round in fewer shots than everybody else, score more goals than the other team, get the quickest time etc, etc. Synchro sports, Diving, gymnastics all need to be re-assessed. You don't get 2 goals for scoring a 30-yard piledriver in football, you get the same as if it had bobbeled in off your knee. You don't get more runs in cricket for smashing it out of the ground, you get the same amount as if it had just made it over the ropes. Basing points on style and difficulty is rubbish and what one judge may think is brilliant another may think is average. I hate that if you attempt a more difficult jump/dive/whatever your more likely to get more points than an easier discipline even if you perform the easier discipline far better.
As for team events, I've no problem with them entering any cricket, rugby, baseball whatever as long as it's done as the pinnacle of that event (it won't be in any of those 3) in which case it should be performed by amateurs.
Rowing is a crap sport imo. BMX is so crap that it should be removed and wiped from the Olympic record