Steinberg did it for good reasons, but went about it the wrong way. So many people work using their systems that they should have had a public duscussion about the issues and updates that were resolved in
vst 3dk.
Superficially, it's not that big a leap. But it was needed, for the sake of keeping Cubase & Nuendo competitive. Having to use 3rd party plugs to do tricks like side-chaining was really starting to get to people, with green eyes looking at how effortless it was to do in P/T and Logic.
From a programmers perspective though, it's only as much hassle as you make it. If you write a badly coded program, it will take more work to port over. The trick is to keep your programs well defined and structured. That way it's easier to break it down and adapt the instructions that need altering.
It will take off eventually. I remember a similar fuss with ASIO2. When dev's have stopped throwing their dummies out of the pram because they weren't consulted, or their plugs are really outdated...then we'll start seing the updates !