Sigh...
Yes, if I were playing the wizard, I'd prefer to set the minis on the grid like in the second diagram, because the second diagram is a larger physical space.
This is disappointing. I'm arguing with someone I agree with fundamentally. Ainatan, I agree with you- I don't like the 1-1-1-1 movement system. But your reasoning with those diagrams is wrong. Don't take my word for it. Lay them out on maps. Find any map in any module ever published, and shift the grid. You'll find that the advantage is nowhere near what you're claiming because you'll have fewer diagonal spaces to work with. You are comparing two completely different maps that will never coincide in play.
Let me try a different angle. Take your second illustration. There are six diagonals across the middle of the room. That means the room is, at a minimum, a 30' x 30' room. Let's assume that's exactly what it is. Now, take the grid (not the room) and shift it by 45 degrees. YOU WILL NOT HAVE SIX ORTHOGONAL SPACES SEPARATING THE MONSTER AND THE WIZARD. You will have eight spaces, and your assertion will not hold up. That's because the room itself didn't not suddenly morph to satisfy WotC's new movement rules- Euclidean space tends to stay fairly constant outside of quantum field effects, something that WotC is probably not fitting into the rules, thank goodness.
There are plenty of valid arguments against the 1-1-1-1 movement rule. Your illustrations are not in that set of arguments. Shift to something a bit more defensible if you want to actually motivate change, please.