The theoretical concern is that some nefarious company will start making improvements and not contribute them back so that it can have access to (and possibly even sell) its own premium version that takes advantage of the hard work of the community without giving back.

Personally, I am a bit skeptical of this for a couple of reasons. First, I have a really hard time seeing any company care enough about uutils to do this. Second, continually merging changes from an upstream project is a real pain, so there is a strong incentive to make contributions back out of self-interest.

But even to the extent that there is some grounds to be concerned, it is not enough for so many people to contribute so much noise to every single one of these posts whining, as if it is attack on them personally.

It's not a matter of "him" personally. Permissive license allow for a work to be taken and redistributed by other entities, without enforcing them to release their changes. This creates a one way relationship that is generally detrimental to the open source ecosystem, allowing work to be stolen away from the public. That being said, choosing a license is situational, and a permissive one can be a great choice in certain instances. For that particular case, I don't see much benefit to having a permissive licence.

Not the commenter you're asking, but I do consider the MIT licence a bad one for something like a core part of an OS. Not all FOSS licences are created equal, there're even important differences between the different GPLs (GPL2 is more permissive than GPL3, for example. With AGPL you have to grant the freedoms to the users even if the software is running out of your server, which isn't a thing with GPL2/3), and even the most permissive ones have a reason to exist, but I'm yet to hear (or read) a good one for these uutils, so I'm not touching any distro or project that uses these mit core utils with a ten foot pole.