Clearly we have, and clearly Docker solved a use case that LXC was in no way solving. So no, we are not "back to LXC", we are two generations ahead of LXC.
All the improvements in containers are happening in the kernel, for instance the long awaited support for cgroup namespaces. Improvements in layers will happen in the overlayfs project with better compatibility for filesystems including possible support for NFS. All this work is happening outside the spotlight while userland runs away with the hype and credit.
None of this matters? It's just the "user land running away with hype and credit", right? Not because all those actually solved an issue for developers, rather than being a random kernel subsystem that you could use if you knew the arcane incantations to summon it, and that only worked on Linux.
A little bit of research will show it's far simpler to use and manage than Docker [1], and because it offers a standard OS environment with support for standard networking, daemons, logging, no enforced use of layers or ephemeral storage it doesn't need an app to hang around and manage its networking and other subsystems.
It offers seamless migration of workloads from VMs, is compatible with the ecosystem of apps and orchestration systems without the need for any special daemon handling, network or storage management that comes from a custom environment, thus simplifying container use and management.
Wait, what's that? It doesn't work on Mac or Windows? It didn't have a even half-decent website until 2015? It doesn't have anything like a dockerfile that you can version control? Or anything to compose services together from a simple yaml file?
Damn. I guess it turns out people don't really care about the technical purity of a solution, they care about something that solves their issues. Better luck next time.