A few downsides to caluperas going sexual:
It is a means of reproduction...so it can lead to massive amounts of un-wanted macro algaes through out your system.
The release of spores can cause cloudy water and a general nasty appearence.
Caluperas are harvested to remove and discard nitrates...when they go sexual the nitrates can be released back into the system...which can cause obvious problems.
I keep a large assortment of macros in my refugium system for the purpose of nitrate reduction/export and I've found that lighting 24/7 prevents them from going sexual...there is always a bit that turns white...but daily I harvest the little that appears to be going sexual and discard it.