"Ignore the app ecosystem and all you've got is a big Start Menu, that's the whole difference."
Wrong. The lack a Start button is actually the least of the problems with the new Start screen. It's simple enough to mouse down to the lower-left corner and click, true enough, and that's what most experienced users will probably do by default. The mainproblems with the Start screen are:
1) It is non-hierarchical; i.e., everything in creation gets splattered all over the screen. When an application installs multiple shortcuts, it's nice to have them associated with that application, not put on the top level by default.
2) It is unsorted and unsortable. I find it logical to sort things in some kind of order, say alphabetically, automatically, without having to shuffle everything around by hand.
3) It is hideous. This is, of course, a subjective viewpoint, but the default available color schemes are wretchedly ugly.
Now, to address the inevitable counter-points:
1) Yes, I know you can re-arrange icons by hand. That's fine when you have only a few applications, but I have dozens of applications with probably over a hundred icons among them. Some sort of default order is called for.
2) I don't care whether my complaints seem like minor objections to you. They constitute a non-trivial impediment to the optimal setup of my primary workspace.
3) I also know that you can install programs to return the Start menu to its pre-Win8 configuration. The availability of those programs does not negate the criticism of the Windows 8 Start screen; if anything, they support the criticism because they indicate that there is a significant market for the return of the old configuration.
"I wish everyone would get over the start screen."
I wish I could ride to work on a unicorn, but that's not going to happen either.