I don't propose nagging users either! A feature is only worth implementing if it provides value, and it should be optional when applicable.
I notice I can follow hashtags on Amethyst for instance, and that adds those "communities" to my global feed. But, I don't prefer a global feed most of the time anyways.
I think the way to incentivize users to employ them would be enabling them to be managed.
This seems like another limitation of NIP-51. Please check out this writeup to see how I believe it could be expanded:
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