you don't need a good DE to do 3d rendering. you can do that with a lousy bane-bones window manager like twm.
1) Lack of good input subsystem (befor you say, but Wayland DO have... It's NOW. Canonical decided BACK THEN. Everybody is wise after the fact..)
2) Putting shell into Wayland protocol. Where toolkits will support it. And where Canonical would need to rewrite it.
3) Lack of interest in Android drivers, AMD/Nvidia binary drivers.
4) All the advantages of creating something in house..
5) Wayland being not ready.
Reasons where there. What I do not understand are people who ASSUME, that Canonical do something out of pure evilness, or selfishness. Or that they should work on project X, because they MUST.
Mir is FLOSS. Whatever they create Wayland can mimic it...
Hehehe,
There are no advantages to canonical creating something in house.
All the software they create is bloated crap, just look at Unity or their SW centre. They are both slow and horrible even on a modern machine.
In addition to this they don't upstream any changes they make to core stuff.
The only upstreaming that has been done is by the community and once they piss them off enough they jump ship too.
Fedora looks better and better each day canonical are sailing in this current direction of pissing everyone off.
From the conversation logs on the #wayland channel, I get the impression that the Mir dev's just did not understand how Wayland works. I'm sure that if they would have approached the Wayland devs and stated their concerns, they would have worked it out together.
To me it just seems illogical for Canonical to waste their time (and money) on Mir, when they could have worked out a solution together with the Wayland devs...
... but they did not even attempt to get in contact with them until recently.