Plus Bosco was the only bear bear we've seen, so bears were probably an endangered species too. Plus Bosco and the sky bison were so damn adorable the Earth Queen has quickly become my most hated Avatar character.
Of course Lin is the only one bitter, Su has nothing to be bitter about. I think its telling that we haven't seen Su actually apologized for what she did. And yeah it was 30 years ago, but in those 3 decades it seems like Su never actually took responsibility for what she did and faced any real consequences. I mean her punishment was what? Go live with your rich grandparents while Toph covers up her crime?
To be fair they were both trained by Toph and Suyin went on a bunch of adventures before becoming a city administrator. Still tho Lin wasn't even operating at 100% so if Suyin couldn't keep up with her in that state that would've been more alarming.
Also, I'm glad that the two sisters didn't just hug it out at the end, because a 30 year long grudge can't be mended that quickly.