I haven't used nvi in several years (mostly because, unlike nvi, vim has become universally available on the systems I use), but it's not minimalist. nvi has a number of features that the original vi does not. Perl integration and infinite undo are two examples.

nvi definitely provides more features than the original vi, just not nearly as much as vim. And it doesn't have a comparable ecosystem of plugin/package developers around it, either.

Is there a popularity dashboard of plugins that one could check to see what features vim users are enjoying that I've been living without?

http://vimawesome.com/ has a list of Vim plugins sorted by their popularity, measured by presence in dotfiles repos on GitHub.

For a conservative list of "essential plugins", see https://www.vi-improved.org/plugins/

"surround" and "targets" are indispensable for me.