Supporting the idea of the jour has development costs.
I'm sorry, how was that? My recollection seems to be that they all got stale and overpriced, and then GNU/Linux ate their lunch.
Today, most of these projects are FOSS, so the risk of another '*nix war' has been negated to the point of being a non-issue.
Go tell that to the users that are not on the few chosen distributions for commercial vendors or without ready made packages on their repositories.
Or the BSD guys that are being left out with some desktop stuff being slowly tied to Linux systems.
All this happens because developers choose to leave out support for certain systems in order to minimize development efforts.
And in regards to the BSDs, what exactly are you referring to? If it's Wayland, that's being ported. If it's KMS drivers, Intel has been ported and radeon is in the process. Nouveau probably won't be ported due to the fact that they already have a pretty stable binary Nvidia driver.
The only two things I can think of that aren't compatible with BSD have both been designed with exclusively Linux by the developers heading those projects, SystemD and ALSA, and even then the BSDs already have suitable substitutions with those, init and OSS.
So, since there's greater cross-compatibility than ever before, how would you suppose that another nix war would erupt?
Mir's only aim is to fragment the Linux community
This Linux community, is a fragment of the Unix community.That Linux community is further fragmented within itself.
The BSD community is decidedly less fragmented than the Linux community.
At this point, who cares what Ubuntu does? If they come up with some better ideas, then those ideas may gain traction within the greater Unix community, and if not, I don't care.
It creates lots of extra work for people who do not run Ubuntu. It will result in extra bugs as things cannot be tested. "choice", short-term benefit of trying to be first. Long term it seems really bad.
And while you may feel as though Mir's only aim is to fragment the Linux community, keep in mind that Ubuntu will be using QML extensively and that will be compatible with Wayland, and through the use of libhybris both Mir and Wayland can target the same display driver.