Solution to a problem that doesn't exist.
The sight glass is in a location that is kind of a pain in the butt to see, so not like you're going to check that often.
The fluid level will only go up if you have the dreaded vampire issue with the leaking cooler loop, but you will have other things indicate that.
The fluid level will only drop if you have a leak, and the leaks are pretty obvious if you bother to look at your wheels once in a while.
The hubs aren't known for heat issues, so no need for a heat sink.
If you want to put them on because you think they look cool, go ahead. As far as I know there isn't any downside to installing them; I just don't know of any real upside either.