I don't really see why there is such subjective arguments here. (Especially trying to "Blame" lazy pros for teaching the shot that the VAST majority of top players now use!)
Yes, there are indeed lazy, ignorant, close-minded pros teaching tennis out there. But, to say it is the lazy pro that teaches two handed strokes makes no sense.
While there are still a number of very solid players on tour with one-handed backhands, the propensity of numbers (now around 92% of the top 100 women and about 77% of the top men), shows the two-handed backhand is the dominant stroke.
That said, I've never had a problem with a player who has indeed mastered the one-handed backhand.
(I'm as objective as they come: I've taught 35 years, personally use a one-handed backhand, taught one-handed backhands for the first almost ten years of my career...and now teach all beginner--regardless of them wanting to become pros or not--two-handed backhands.
Read my earlier post too: It is EXTREMELY rare to see a player first learn to hit two-handed not be able to hit one-handed backhands well. Nor do I find it a difficult transition for two-handers to move to a one-handed backhand if they find they just feel that is their stroke. HOWEVER, I have seen hundreds of players who first learned one-handed try to learn two-handed backhands with far greater difficulty and usually with most reverting back to their inferior but more comfortable one-handed backhand.
I won't label one backhand "superior" to another. However, I think I have enough experience to be able to say with certainty, that as a general learning pattern, the two-handed backhand works not just for those kids in the 8's, 10's and 12's be more successful, but that the stroke works for most players of all ages, far better than teaching the one-handed backhand.
If you talk to any qualified pro who has been around for a while and has produced successful players, ask them if they had 100 players and wanted to give all 100 the best chance at hitting backhands well, which shot they would teach.
Almost without exception, these pros would teach the two-handed backhand to those 100 students.
Dave Smith: Author, Tennis Mastery/Coaching Mastery;
Senior Editor, TennisOne; Dunlop Master Professional