There are several different reasons why someone may want / demand more watts than what has sort of become the standard answer for "How many watts does a gigging bass player need?" - which is around 500WRms @ 4 Ohms.Yep. Personally, I've made the leap into using a multi-effects processor (Darkglass Anagram). So I'm looking for clean & reliable power. Good tone would be a nice extra, but wattage has risen in importance. I bet there are a lot of bassists in my situation.
Some speakers are less efficient and require more watts to get them to gigging SPL.
Some bassists use a lighter touch when playing which means the beginning level is lower, thus requiring more watts to get them to gigging SPL.
Some bassists believe that more headroom from certain higher quality amps gives the notes more substance or heft even though the SPL is not higher than what a lower powered amp would provide.
Some bassists play larger venues &/or outdoors gigs without PA support and their on stage rig has to provide a level that works in almost any situation.
There may be other reasons, but I think this is a good start (all four of these have been my personal experience).