But shouldn't the cursor change to a hand cursor rather than an arrow
cursor when hoovering over a mouse-face?
I think the change was a mistake, instead we should have arranged the
relevant areas to have both mouse-face and pointer text properties. But
I don't know how much effort it will be now to go back and change this.
I haven't followed this thread closely, but this does indeed sound like a
(design) mistake. The two, mouse-face and pointer shape, should be
independent, by default. If some particular code wants to couple them for
some purpose, that's fine, but such a coupling should not be hard-coded or
the default behavior.