I think the Touch Bar has potential, to be honest. The main selling point is that it offers apps a way to make previously hidden functionality much more discoverable. The traditional row of function keys is flexible and simple, but it also places a lot of demands on the user -- it's up to you to research what each key does in all possible contexts and to commit that to memory. The odds are very high that there exists at least one context in which some function key performs a function that would be useful to you but you weren't aware of it. The Touch Bar could be a remedy to this situation.
That said, I haven't used it and don't want to sing its praises too early. But I also don't want to wish it dead on arrival.
They are actually 2 modes (you switch between the OS keys and the Fx keys by pressing the fn key). There is also an OS setting to switch which mode is enabled by-default (without pressing the fn key).
Right, so TouchBar increases the number of possible modes to basically infinity. Isn't there already a way to make the TouchBar just render the function keys?
Yes. Now the Touch Bar will (by default) display the function keys when the `fn` key is pressed, and display the current set of functionality per the application otherwise. There is, per the presentation and reports, an OS setting that allows you to switch which is the default.
One of the first things I do on a new Mac is to toggle the preference that lets you use the function keys and function keys and the "fn" modifier to coerce them to do things like volume control. Macs (until now) absolutely do have function keys for anyone who wants them.
That said, I haven't used it and don't want to sing its praises too early. But I also don't want to wish it dead on arrival.