Good point! Unless one gets paid, maintenance is a hobby. Few people can afford putting a lot of effort into it. And it comes at no cost to us, so I think even if it's not perfect, it's damn good quality for a free system!I don't know the cause. I just know I keep running into ports that are old or take weeks/months to be updated. I'm speculating. There's no way I have time to update every single port I come across. If it's as simple as just tweaking the Makefile to another version, and doing a pull-request, sure. That's not been my experience though.
What would motivate well to maintain a port would be in my opinion one of two cases: (1) someone needs it badly for private purposes, maintains the software and shares with the community; (2) a company needs it to do its business, so it sponsors developers to maintain the software (for example, iX Systems and FreeNAS).