The Zoom+ button is the one I use most often in plot windows. Why removing this one? Does it make fun to annoy users?
It's the same as with Microsoft, Gnome, Mozilla etc., they just remove very commonly used features, without replacement, without option to configure it back, sometimes even without notice or reason. Menu bars disappear, symbol bars disapear, frame borders shrink to zero size (very confusing for overlapping windows), status bars disapear .... Why not delete the software completely?
I understand the motivation to give individual controls to subplots. But please leave the common symbol bar intact, at least as an option (View settings -> Zoom toolbar).
Matlab is used for experimenting in research and development. Ad-hoc and interactive work, with some plots in between, mostly single plots, not subplots or GUI. The option to create some GUI apps is nice, but it's not the main application area for MATLAB.
The "accepted answer" is a quick-and-dirty workaround about the problem. It still does not remove the annoying fading effect in subplot-figures.
Don't forget, people take MATLAB because it's user-friendly to open a measurement and zoom into the timeline. If this is not comfortable, there are also other alternatives, like Octave and SciPy ...