It's really not that hard to toxic most of an opponents team even without toxic spikes and toxic spikes are pretty easy to remove anyways so I dont think that's too much of a problem (heal bell/ aromatherapy use is pretty common too). The reason mollux really needs toxic spikes is to provide him 1. with reliable poison stab through venoshock which is really vital to the concept and would help him become a more effective bulky offensive mon. And 2. Allow him to use his bulk and typing to give status support to his team. Also with these being the two main roles of mollux it makes toxic spikes a vital portion of his moveset as he wouldn't be able to perform them as effectively without it.