Umm, how are you not using your personal likes or dislikes to judge canon? You don't like the changes to Forgotten Realms, thus don't accept those changes. You don't like the changes to elves, thus reject Eladrin. You do like the changes to Dragonlance and thus accept the changes. I'm still confused what the difference is.
When I look at story changes I have to consider; 1) does this use something that exists already even if it maybe in a new way. If it does then usually it is going to be OK. For example Szass Tam turning Thay into an Undead wasteland. This seems like it could be plausible canon change even though it goes against what I would prefer. 2) if it does not already exist, is it plausible that it may have possibly existed just not previously mentioned. The Shadovar fall into this category for me, creatures that as far as I was aware did not previously exist but it is possible that they were just living in the Plane of Shadow until now.
But what about Eladrin? They did exist on the Planes so it is possible for them to travel to Forgotten Realms like the Shadovar. But they did not, instead all High Elves were revealed to be actually Eladrin all this time. Surprise! Bet you did not see that coming after all those years of Forgotten Realming.

So Eladrin fail both the canon change test as well as my personal bs sniff test.
The Dragonlance canon I have explained already so no need to belabor that tired point again.