With this change, you have just forced druid players into a support role, just because they selected druid as their elite spec. I thought Anet was all about build diversity and opening up more build options. What if somebody wants to play a druid dps build (which IS a thing, btw), you just nerfed the puppy out of them!! When I play druid, I choose it because of the traits, not the profession mechanic. You should NOT penalize players for build diversity.
I am very ok with the whole trade-off philosophy as long as EVERY elite spec gets the trade-off revision. The update notes mention Necro elite specs as an example of "clear trade-off"s. Those are NOT trade-offs, they are clear upgrades! The elite spec shroud skills are far superior to core shroud skills. What does the Necro actually lose? Nothing. But I digress, that discussion is best left for a separate post. For the druid trade-off, instead of killing druid build diversity and forcing them into a support role, activate the trade-off only if/when a druid uses the extra mechanic. A druid who doesn't use Celestial Avatar is not really a druid, and should still be in touch with their pet. However, if they activate Celestial Avatar, they are translated into a new state of being where their connection to their pet decreases. So please give them the pet attribute decrease ONLY when in Celestial Avatar form and maybe even for a few seconds afterward, while the bond is reestablished. For puppys sake! Don't kill build diversity!