I'd be fine with some kind of election mechanism built into subreddits settings that could be turned on to allow community member to vote on mods.
With that said consider a subreddit for a podcast or youtube channel where the host/channel might legitimately want to have total control over moderation and I don't think it'd be appropriate to remove them.
Also consider that the vast majority of subreddits are moderated by volunteers who are only doing it because no one else will. You'd probably get more milage out of a way to force community members to take turns serving as moderators than you would having a mechanism to remove existing mods.
When someone says Reddit moderator you're thinking of /r/news or /r/funny not the person running the sub for their favorite book or local sports team or interest group. There are way more of those moderators and you almost need to handle the two use cases differently.
For the truly top subreddits I think Reddit should be employing people directly or indirectly to do the moderation. At the very least they should be compensating those people and reviewing their performance.
Reddit should also make better mod tools and do way more to help with moderation. It's offensively bad what they offer today. If Reddit actually gave a damn they would force every software engineer at the company to spend 2 weeks as the moderator of a subreddit once a year and I guarantee this problem would be solved quickly.
I also think some semblance of moderator hierarchy would be extremely helpful. Have some sort of mod council that oversees all of Ask* subreddits and another for sports subreddits and another for NSFW subreddits. Those content domains will all have similar needs and having someone looking at the bigger picture across individual subs would be very helpful.