I think it's fine for ANY one to have Yorkie or any other small dog. My best friend has always had small and big dogs since he was little. As he's gotten older (now just turned 31) he has a Maltese and is considering getting a Yorkie or another little dog. He just likes the smaller dogs because its' easier for him to take care of and they don't mind him having to be away for work.
I was in Petsmart yesterday too and apparently it was small dog day with their male owners because it was packed with poodles, yorkies, and chihuahuas. There's even a very macho/athletic type of man that goes to my vet and he has this teeny tiny chihuahua that he thinks he and I need to set up on a date.
My thought is if you love your dog, that's all that matters and poo poo on anyone that says differently.
Dana & Bella