This makes me chuckle a bit after reading countless posts on numerous forums asking for an M&P that was G19 size.
Essentially, you want Glock to make a gun that is M&P 9 full size, and one that is M&P 9 compact size.
Don't get me wrong, I agree with you. I've often compared the G19 to a smallish college defensive end, who ends up being a "tweener" in the NFL - too small to play defensive end, and too slow/not athletic enough to play linebacker. I think the G19 is kind of small for a duty gun and a little large for a concealment gun. M&P does a much better job covering those bases, in my opinion.
I think the M&P is a more useful full size gun than the G17 and G19, and the M&P 9 compact is a better concealment size than a G19 and more useful as a shooter than a G26.