Happened to find the pull request discussing the lxc-driver issue. It sounds like there was some interest in contributing upstream, but it didn't really go anywhere.
https://github.com/docker/docker/pull/5797
From the thread, it seems like the concern was just that lxc-exec wasn't well maintained and the lxc interfaces weren't stable since it was undergoing heavy development. I think that's changed recently with both lxc and docker now post 1.0 release and 'production-ready'.
Docker still uses LXC if you want it to via the lxc-exec driver and the --lxc-conf option. It's just not the default, which probably makes sense since the lxc options mainly apply for advanced users.
So by default, Docker uses libcontainer for a simpler installation experience. But for advanced users, using the lxc driver is an option to look into.
IMO, Docker wins if it continues to play nicely with the other open-source projects people use with Docker, and also give credit where due.
Docker still uses LXC if you want it to via the lxc-exec driver and the --lxc-conf option. It's just not the default, which probably makes sense since the lxc options mainly apply for advanced users.
So by default, Docker uses libcontainer for a simpler installation experience. But for advanced users, using the lxc driver is an option to look into.
IMO, Docker wins if it continues to play nicely with the other open-source projects people use with Docker, and also give credit where due.