Some developments require deep changes in the C++ code. They impact various parts of the software in various ways and lots of testing has to be done to keep the software consistent and bug free, even before entering into a beta-test phase.
Also we try to make sure that everything will be scalable in the next years, that's very important for all the TVPaint users.
As a consequence, such changes can't be done into smaller updates, well ... unfortunately.
That said, regarding the v11, I think you might have more smaller updates in 2017 than in 2016.
Fabrice Debarge, Product Manager, TVPaint Team