I think you have a point there, but the reasons why Mint does not ship a streamlined version may be simply because the maintainers don’t want to bother with a whole different context to build, document and support.
I do think there would be value in a less “batteries included” Mint. I disagree with people in this thread who claim the “whole purpose” of Mint is all the stuff it packs, because it goes far beyond the essentials. Mint develops a lot of GUIs for the user to be able to configure the system. I think just these plus the in-house Mint core apps would make for a sweet, lightweight and less bloated system that would have real appeal, but that would also mean more work for the Linux Mint team and perhaps it wouldn’t really mean much for their audience.