I think the devs and people like you are missing the point. We understand it a choice but this effectively is saying because we grinded out destines before u20 we are going to be penalized for it via them removing our "work" thus making us waste our time trying to improve out toons.
If you can't see this your not even trying, it's like them saying we are going to change how completionist works. Instead of just TRing you need to do an extra step in the TR process and since you TRed and got your XX amount of PL when this "extra step didn't exist" we are going to take this away from you like you didn't do it and you will have to regrind those PL using the new "method" or lose your completionist. We know it sucks but it's okay though as you "don't have to do it".
The above is vastly different than them adding a new class and saying to keep completionist you need to get that PL as this doesn't invalidate your previous efforts.