I don't think he's responsible for the "unhealthy and abandoned dogs out there." In fact, whether they are pure breeds or mix breeds, there have always been "a lot of unhealthy and abandoned dogs out there."
I don't think he has any reason to apologize. He bred a litter for a good reason and it's not his fault people are silly and only want purebreds. Hindsight is 20/20 and obviously if he'd known what would result he never would have coined the term "Labradoodle".
Also, how for the people that the gimmick actually worked on... how does a ridiculous name make the dog a purebred? Mix breeds are great, but they are not purebreds. It always drove me nuts as a student when people came in with a "Labradoodle" and wrote that in the spot for "Breed". I remember once I asked someone if their puppy was a "Golden cross Poodle or a Labrador cross Poodle". He informed me that the dog was a purebred "Labradoodle". Being a little less tactful at 16 I asked "So his mom was a Lab and his dad was a poodle?" To which he answered in the affirmative. I then wrote in the breed spot of the paperwork "Labrador X Poodle" to which he got very upset.
The entire craze was a completely unforeseen chain of events and I think it's extremely unfair to consider him responsible for all of it. I mean, this list of "designer dogs:" http://www.dogbreedinfo.com/hybriddogs.htm
I really suck at estimations, but there are definitely well over a hundred different crosses there. That didn't happen just because some guy bred a lab and a poodle.