No breed of dog is perfect so why go on to cross 2 breeds to create another that will have the bad points of both breeds?
What may suit one person may not suit another - The perfect breed for me is far from the perfect breed for anyone else - But there are plenty of well established breeds for people to chose from - yes you can cross 2 breeds or create a new one but it will take many years before a breed standard will be acheived - what is missing from the already huge list of breeds???? I dont think there is anything missing, there are plenty of breeds available to suit any life style these days - all these breeds have history and not many are still being used for the original purpose but fit very well into todays life styles.