Interesting point.
Can't say I've hit many of the newer Mizuno CB's but I play the MP 20's (which I love) and go PW-6 in blades and then into the HMB 5-3 as the MMCs didn't launch any higher or feel anymore forgiving than the blades in the longer irons. Would like to go CB in the 6 too but HMB sole is too big. Lofts on MMC felt too low and topline just as thin as the blade so didn't boost confidence that I could get it up in the air. Don't think it's just Mizuno that have fallen into this trap either, Titleist CBs are basically blades in size and profile now too.
Feel like manufacturers have listened to a few of those that shout the loudest too much so have all gone thin topline/no offset which although might sound great really isn't very good for most. CB's therefore feel like they've been squeezed so much now that if you don't like a pure blade you'll be forced into a hollow iron of some sort with low lofts and quick faces.
I think this might be why the recent Srixon CB's have been so popular, slightly larger footprint, thicker/more confident boosting topline and genuine forgiveness, a proper forged cavity back.
I also like the idea/way they used to do the slightly more forgiving, larger blade every now and then like you point out. Haven't hit the MP5 to my fault but reckon the Titleist 695MB (not dissimilar in size) is the most forgiving blade I've ever hit, new Titleist blades look like scalpels in comparison. Quite alot of older blades were actually quite big in reality compared to blades now. As long ago as TP19 even spring to mind. Recent Mizuno blades although all in their own right look great imo seem very very similar. New S1 might offer slightly different CG with high muscle ala MP5 (but smaller) but other than the finish, the profile at address looks basically the same again.....though they do look very nice.