Getting hung up on labels only makes life more difficult. Using a different word to describe a condition (i.e. "differently abled") changes nothing.
Except we are differently able. The point of using that phrase is to emphasise that, rather than to emphasise the opposite.
Your points are often useful and well observed, but there's also often a kind of tired of it all negativity that clouds your conclusions. It's not so cut and dried, we can leave room for other ideas that can sit side by side with our views.
We are differently abled. And sometimes it can be a big advantage to see things differently from the majority.