I was thinking that too. I was really pleased with what they were able to do, especially given their circumstances. Everything did feel rushed near the end, but considering how few episodes they had, the budget cuts, it all makes sense. I was kinda disappointed there wasn't more of a nod to Avatar, like even having Toph or Katara return would have been good.
Nah, that was addressed already. As Toph said, they're too old for this now.
Yeah, but on the other hand, remember Iroh and Bumi from the original series?
I got the sense that Iroh was just a little north of middle aged (like Tenzin or Lin), and that King Bumi was a major exception. I guess Pakku was pretty old too. The old folks of ATLA's Order of the White Lotus only engaged in a relatively smaller battle in the grand scheme of things anyway and left the boss battles to the gAang. And keep in mind, this was to end a century-old war of global scale when it looked like the war was about to be lost to an obviously evil and unhinged dictator.
For better or worse, the Korra plot was much lower stakes. While arguably global as well (given the breadth of the Earth kingdom), conflict was much more contained since Kuvira's mandate was Order. The conflict has been going on for less than 3 years... arguably more in the span of months, because Kuvira hadn't actually gone against the other leaders until the third episode of book 4. Even though she had done some terrible, ruthless things, she had begun with good intentions and pure motives. Even when she was doing evil kinds of things, she wasn't really evil herself. And she was sane. Katara didn't need to get involved. Toph didn't fight in the final battle, but she still had some meaningful contributions earlier in the book.
Actually, my biggest disappointment is that we saw so little of Zuko's daughter. It's not even clear if she has any sort of battle prowess... I mean, it's probable given her father and her son, but it would have been nice to see her electrocute some mechs or something.
One of my favourite scenes in the finale was when Meelo was clinging to the window of the giant mech.