All the reason to avoid trying to overfly large cells, and definitely not if they're producing red returns. I used to be pretty nonchalant about doing it at FL450 in corporate jets but in the 30s you can get swallowed pretty quickly. I learned that lesson coming back from Dakar one night after step climbing over the Atlantic to get some more margin over some cells that were topping off in the low thirties. Until suddenly the lighting flashes that were below us started being above us. Thank goodness for CPDLC that allowed Santa Maria to approve our deviation within seconds otherwise it would have been the first and only time in my career invoking the oceanic weather contingency procedures.