My guess is because developers were disinterested in making use of it. It comes across as a gimmick, as mentioned above, but mostly because it was hardly utilized for anything truly productive. As a developer myself I completely loathed two things about the TouchBar; 1> already mentioned, other devs not capitalizing on it. If I were doing Mac Apps, I would have been all over it. 2> They took away my physical F keys and ESC key. WTF? Apple began waging a silent war on the Escape key a few years back and I’m not sure just what their deal is. Too many apps use it far too regularly. That’s my most hated thing about the iPad Pro that I spend hours and hours on. No Escape, so now CMD+~ is embedded in my muscle memory.
Anyway, Apple themselves didn’t seem fully willing to commit to TouchBar. In order for it to succeed they needed it on all their notebooks, not just the Pros and they needed it on their iMac keyboards as well, specifically the iMac Pro. And when their own apps fail to use it for any real function where it would be obvious, well… they killed it.
