I am not positive but it seems like the difference between a morkie and a yorktese is which side the male/female is on. Like a morkie would have a maltese sire and yorkie dam and a yorktese would have a yorkie sire and a maltese dam. I may have them mixed up but I think that is the difference.
I personally wouldnt pay as much for a mixed breed as I would for a purebreed but I would probably pay a reasonable amount for a morkie if they are as cute in person as some of the pics of them that I have seen. The ones I have seen pictures of remind me of a blond cocker coat color and have big expressive dark eyes. They are one of the few mixes that I would buy. Just so cute!!! I think I read somewhere that way back when - yorkies had maltese in them to start with.
I currently have several yorkies and had a maltese in the past and would love to have one again someday. My yorkies for the most part are more hyper then my maltese ever was. She was lap baby all the way! If mixing the two would result in a puppy that looks like the pics I have seen with a calmer demeanor - sounds like a wonderful little dog.
As far as only the people breeding show quality should breed - whether it be a yorkie or any other breed - if that was all that was out there few of us could afford them! I agree that breeders should strive to meet the standards for the breeds but look at all the ones that are outside the standard that we all love just as much.
As far as what you call them - a rose by any other name would still smell as sweet, to borrow a phrase. So, call it designer, mix, mutt, whatever just call it to come and bring all its puppy love with it!
Guess I am rambling now. Good luck in your quest for a morkie!