WordPress Housekeeping is a responsibility of site owners and managers. Having themes and plugins around – even if they are not active – is not good for your site.
But if you need to keep inactive plugins around, make sure to update them when called upon. Failing to do so creates an unnecessary security risk.
Recently, I started using WP Update Notifier on client sites. Every time a plugin needs to be updated I get an email that lets me know which plugin needs attention. Very handy!