GH, I have nothing against mutts either, but I say if you want a mutt go the animal shelter; don't breed your own. So many of these 'designer' animals wind up there anyway, so if you're determined to get a Sheltipoo or some other mish-mash you can find one without having to pay some exorbitant price. Same goes for horses. Plenty of 'hybrid vigor' grades in rescues and at auction. No reason at all to breed any more of them.
Agree to a point, one example, I love Haflingers, and to me they should be short square little ponies/horses, and I am really sad to see them creeping up above 15hh, it is just wrong. In a way I would rather see someone having a program to breed Haflinger x TB for instance, to fulfill that market.
I am happy enough with a first cross, bred for a purpose, but you can't keep adding a touch of this, and a pinch of that hoping for the best.
Blazing, you have not made your point or defended it well, I don't see what you are going to bring to the horse world with your aim, you say you want:
good size but not huge, just big enough to get over higher obstacles but small enough a short person (4'9-5'6) can get on without much difficulty.
A chunky type Arab will do all that, or a QH, Welsh section D, Andalusian, and loads of others that I haven't thought of yet, no need to design something to do it all, they already exist.