In the future, I feel if we have these types of instances that some form of gating would be help prevent guilds with a limited schedule from becoming too discouraged. If not by wing (I know that is contentious), then maybe a 2 week period prior to heroics being unlocked.
T14 was really nice because there was a natural "gating" created by the step-up between MSV and HoF/Terrace. I really liked that model. Totally agree that every tier should be different and it's okay to have a big mega instance. But doing it with no throttle and then throwing in the most time consuming and difficult trash that I've ever seen in a WoW raid.. that was kind of overboard.