Yoke is simply more practical for places like Caribbean resorts. Din valves can't take nearly as much banging around; they can get knocked out of round, the threads get knackered up, etc. As Lorenzoid mentioned, the yoke inserts are problematic because they are unprotected threads, and if they're not removed regularly, they easily get corroded in place. Then you show up with a DIN reg and they try to take the insert out on a rocking boat with a rusty allen wrench....I've seen it happen a few times already where they just couldn't get the inserts out.
In a perfect world, where all scuba tanks were handled carefully, and all the inserts were taken out every day, sure DIN would be great. But that's not reality. For tech diving, the shops are generally much smaller, tanks generally handled with more care, and they don't use the inserts.