After having asked "You can only post once every 40 minutes": Why is this timeout applied to a site *and* its meta? Should it be? and fallen down the rabbit hole of duplicates therefrom, I think I have a suggestion that would enhance user experience in the remarkably common case (three duplicates! three!) of "user posts question there's no tag for (that is otherwise on topic), but cannot ask for the tag on meta because they're rate-limited": Separate rate limits on posting for main sites and meta sites. I feel like this preserves most of the spam-preventing functionality of the rate limit, while being less likely to cause genuine users to smack straight into it if they need to make meta requests. (I would also accept some other means of requesting tags (thus obviating the need for this suggestion) as a reasonable answer here.)
No, I don't think the communities overall will benefit from this separation of rate-limiting. The Stack Exchange sites, including site meta, cater for quality over quantity for their future visitors.
Questions asked in quick succession are more likely to be riddled with poor research, lack of attempt to solve an issue at hand, grammar and spelling issues and doubtful usefulness.
Allowing oneself 40 minutes to formulate a proper useful question is not over asking nor is it a bad user experience assuming receiving close and downvotes for a hastily asked question is a less ideal experience.
SE sites and its users are not a fire brigade with quick responder teams. Nothing that is posted on Meta needs action or resolution within 40 minutes and if it does you're using the wrong tool. Use flags or chat for those cases.
Even if you're arguing that requesting new tags should be exempt from this rule I beg to differ. Tags are there so the experts can find the question. Choosing the right tag, excerpt and wiki is hard. Various examples on MSO prove this on a weekly basis. Getting rid of wrongly used tags is even a bigger headache. So if it is ever considered to lift the 40 minute rate-limit for meta sites, at a minimum exclude questions that ask for new tags, synonyms or burnination.