This isn't just a Mac issue, really ....
I mean, yes, it apparently is in VLC's case -- but overall, have you ever really looked around on a web site like SourceForge, where all the Linux development projects seem to "go to die"? It's depressing, really. I've so often found a great open-source project someone started as an alternative to a commercial product, only to see that it was last updated years ago, and is basically in "life support" mode with no active developers.
(As just one example, I found a French guy who started working, years ago, on a freeware alternative to the Symantec Ghost Enterprise product for Windows. It let you set up an imaging server and image, or push images out, to any PCs on your network. But nope -- the project seems to have stalled due to lack of interest in coding it any further.)
I think the truth is, a lot of this software is really difficult to write, and only gets done because a few people with a specific and deep skill-set in that area decide they want to work on it. In the case of VLC ,you need people with a LOT of specific knowledge on how various codecs work and on all the intricacies of various image formats and variations out there. You have to know just as much about the AUDIO side too, if you want things like Dolby Surround 5.1 decoding to work properly on movies, etc. etc. What's the chances that these same people have a wide enough base of knowledge to code for multiple platforms? They usually DON'T, so they get stuck and have to ask others to step in and help when they get to wanting to "make a Mac version" or something else. When there's no money involved, it's tough to get volunteers to step up and commit to something like this.
At least in the Linux world, you have some of the companies selling specific Linux distributions who have enough interest in seeing certain projects thrive that they kick some money in, to keep developers working on them. (RedHat does that often, for example.) On the Mac side of things, it's not like Apple is going to pay out money to help someone compete with them!
Very bummed out. VLC is easily the best all-around media player that requires virtually zero effort to use. As good as quicktime is, I find that in order to play a lot of alternative video formats (matroska, etc) it requires a heapful of external codec downloads and plugins, which don't always work the best.
Hopefully it's not a sign of a dying breed of mac developers, but this is the exact problem that has plagued Apple for decades - there just aren't enough developers writing MacOS software to entice the bulk of consumers & businesses to use the platform.