Except for any compliment for the dreary Muppets From Space, I pretty much agree with you. While I liked Muppets Tonight, it really was like having a Muppet Show without most of the Muppets.
I see that standpoint. The problem with Muppets Tonight was that it was trying to rebrand the property after essentially losing most of the characters. Kermit was strangely on a limited use basis at that point, and quite honestly, he wouldn't have worked as the host with the format. That weird talk show/sketch comedy thing. Which was a strange and indecisive format anyway. Though I'd say that the parody segments (for the most part... the Pig segments were lousy) here were much more hip and well done than some of the stuff in JHH. If MT was a little more like a polished version of JHH, it would have worked better, and Kermit would have been a perfect host. In MT, he'd just be that awkward, trying to be hip Kermit that said, completely out of character, "Get down with your bad selves" in MFS.
That said, they certainly had full use of Steve, Dave, and Jerry's characters. They should have used more original characters in silent cameos, sure. But I'd say a good amount of the new characters made for the show were quite good. Just... the pigs...the
pigs... well, maybe not Howard Tubbman. That was actually kinda funny. But Spamella and Hasslehog were even more vapid than what they were parodying. Worse yet, when Miss Piggy was involved in the skit, they just ramped up the overly jealous schtick and let the fat jokes fly.
Dr. Phil is about half and half for me, because I really enjoyed him, and he wasn't a carbon-copy of Bunsen, but "Tales from the Vet" was too close to Muppet Labs.
They tried to regenerate Pigs in Space with new characters by spoofing Star Trek, Next Generation, but Pigs in Space without Link or Dr. Strangepork is just kinda blah.
David Hogselhoff could've been entirely replaced with Link Hoghtrob, even though they wanted the name parody of David Hasselhoff.
Well, considering Link wasn't fully recast until a video game, and didn't actually get screentime in anything until the movie before the last one, that would have been impossible. Strangepork should have been there, and he actually was in one Bay of Pigs Watch, but what made PIS

D9 unfunny was forgetting what made PIS funny in the first place and just had Andy and Randy run around like idiots.
As for Tales from the Vet, I'd say it's completely different from Muppet Labs because it was more of a horror comedy angle. VanNeuter was different comedically than the mild tempered Bunsen Honeydew, and the humor focused mostly on VanNeuter getting the brunt of the physical humor. Muppet Labs was more about making fun of scientists who build stupid, impractical inventions and seeing them fail on Beaker was most of the humor. TFTV was more about mocking
mad scientists and humiliating VanNeuter along the way.
Still, a more nuanced approach to this series would have been a blend of old skits and new. Some of the new stuff was actually pretty good. The stuff that didn't work
wanted to be the old show in all the wrong ways.