Isn't this kinda expected? Most sites have fairly 'boring' needs, and hence the plugins they use solve 'boring' problems. Like a contact form, improved SEO or security, etc.

If you did a similar survey for the most popular plugins for almost any other CMS, I'm sure the results would be similar. Mostly normal business site logic, the shop system of the day (unless the CMS is for a shop itself), and some minor fixes to things people find lacking in the default settings.

For other examples, one of the most popular vBulletin plugins/mods back in the day was VB SEO, a paid SEO system that was basically the Yoast/AIOSEOP of its day, and one of the most popular XenForo plugins right now simply adds a bunch of BB code options for other video hosting sites and services.

Heck, even real life kinda does this. If you polled people about the 20 most popular home appliances bought in the last 10 years, the majority would be 'boring' things like a kettle, toaster, microwave, washing machine, fridge, etc. Nothing wrong with that, just that for most people, the most 'original' appliance equivalent would probably be a video game console, and the rest of their needs would be just the usual domestic house stuff.