I don't like how the ATP have grown more and more reluctant at the thought of upsets over the last years, and grant the top players all sorts of advantages in order to keep the ranking summit stagnant.
I don't mind having 32 seeds rather than 16 in slams, even though that step was taken for above mentioned reason.
BYEs suck, and it should definetely not be used in these small tournaments, where as many lower ranked players as possible should get chances.
In a way this is a consequence linked to the homogenization of the surfaces. As the same players go deep in tournaments week in and week out they are granted cons to not wear out completely.
I'm also against mandatory events. Every player should be able to schedule his year exactly the way he see fit.
Furthermore, bring back indoor carpet as a surface, have more grass tournaments, and make the clay season longer and not too tightly packed.
However, at the end of the day, there's way too much money at stake from all corners for any of these points to be heard.