Some plugins are only used by a few people, not the whole users in the enterprise. For example,
https://marketplace.atlassian.com/apps/1220747/swagger-ui-for-confluence?tab=pricing&hosting=cloud
This plugin is extremely helpful for API designers, software engineers, and testers. But how many people are designing API in an enterprise level? If I have 1000 users on different confluent spaces, probably only one or two space users will use the plugin to edit and design API specs, and that would be way below 1000 users, probably less than 20 users.
If Atlassian would change the license pricing model for license, I think more plugins will be installed and purchased that matches the exact number of people that uses them.
I hope Atlassian reconsider their plugin pricing model.