Yeah, I get that the current ArcMap/Globe/Scene/Catalog products couldn't be upgraded to 64-bit - either technically impossible or so complicated that creation of a new product was likely easier and would deliver better results. So I do agree that the creation Pro of was necessary in order to bring about 64-bit Desktop GIS. I think the biggest challenge Pro faces and why it has disenfranchised so many users is because it radically changes every, single GIS workflow. Almost nothing remained the same.
Going from ArcGIS for Desktop 9.x to 10.0 for example, Esri made some pretty big changes; feature templates, python addins, catalog, python, search and toolbox windows, etc. Those were all pretty radical advancements at the time. I recall tons of users griping about the change to the editing workflows with the introduction of feature templates. Eventually though, everyone was able to wrap their head around those changes because the rest of the product and workflows pretty much remained the same. It was incremental progress.
Pro however, has flipped everything on its head. The two products might look somewhat similar but in terms of how you get things done, the workflows are so different that it's incredibly hard for seasoned GIS folks to wrap their heads around.
I think Esri would have done better to just start off with 'ArcMap Pro' and 'ArcCatalog Pro', then little by little worked in ArcGlobe and Scene functionality or continued with the paradigm of a suite of applications.
Alas, it is what it is. It's Pro or Bust for Esri and that's fine.
I suppose we'll either all get used to it or slowly start spending more of our GIS budgets with Boundless instead of Esri.