You can remove the inlet side (rear) airbox boot. You'll get more induction noise and the filter will be exposed to water & more dust than it would have been. If you don't ride in heavy rain it's a non issue. Might need to wash the airfilter foam more often but that's no bfd either. Unless you're out riding lots of miles in the dirt, once yearly cleaning ought be mild overkill.
And, yes, old rubber parts can become crunchy in the extreme. New airbox boots are still available, as are cannisters, with new boots installed.
And, yes, old rubber parts can become crunchy in the extreme. New airbox boots are still available, as are cannisters, with new boots installed.