No, what I was saying is that when someone does an attack that would time itself with the end of your buff duration, it is better to hit Recuperate because it would give you a 15000 HP buffer than to use Impalement. Like if MNK inputed Phantom Rush in such a way that it would time just as it ends.
The changes have downsides as you listed them, but also benefits and it is essentially changing up how you play DRK as a whole. Whether or not you want to relearn this is up to you.
You can react-Guard now when you had to predict-Guard and potentially whiff it entirely. Inversely, the end of your Guard timing simply now matters and you need a backup plan that isn't "I press Quietus/Impalement" - or you need to plan your HP management better and improve your gameplay so you don't get caught like this in the first place. You gained options and lost some and it is up to you if you want to accept that or go play Warrior for example.
If you are tanking on crystal, you should ideally do this with the following conditions:
1.) Salted Earth can be used (Mitigation + regen dome for yourself)
2.) You try to hold in an area where you can walk back and forth with a wall/pillar for LOS protection
3.) At least one stack of TBN available
4.) At least 5000 MP available with (close to) full HP
5.) Impalement in reasonable CD distance (1-6s CD remaining)
6.) You aren't going into a 1v3 crystal hold (exception if Overtime is happening)
You have more than enough tools to be a tank and your Guard can still be quite powerful - you just can't do Guard -> Impalement at low HP. However, you CAN do it at 50-75% HP remaining if you predict the enemy is trying to hit you hard as soon as Guard ends, because the increased damage and therefore increased lifesteal snapshots as soon as the hit lands.
TL;DR: You have to be more proactive with your tools, DRK can still tank - you simply have to learn how in this new system.