We want to ensure people have a good experience and the heavier the sticks are, the harder the build will be physically. It also increases the risk of a pop-out during construction.
32mm is a good max size as it keeps the weight manageable and maintains a nice proportional relationship between the hubs and the sticks.
Generally if you don't mind dealing with more weight or risking pop-outs during construction then you can go for it. Get a few more friends to help, and if a stick pops-out - just pop it back in!
Note that if you screw your ball connector on slightly off-centre then there will be a bit of an overhang and it might not look so nice. So a bit bigger is better to give you some room for error!