I'm inclined to agree. None of your points hold any water with me. These sequels are ungraceful at best, but they are by no means inferior to their predecessors.
Simon's Quest, on the surface looks pretty bad, but it's actually not terrible. It may seem cop-out-ey but a lot of games like that, at the time were "Nintendo Power Games," meaning you needed a subscription to Nintendo Power in order to learn all the secrets (this being an era before walkthroughs or the internet) Yes, it was cryptic, but was it any more cryptic than the original Zelda? Let's not forget, you're just thrown into a world with no indication of where to go or what to do in the original Zelda. That too was a Nintendo Power Game. And much like Arin Hanson said in his Sequilitis video, Simon's Quest is one of the earliest games that use gameplay to set it's tone. I agree with his idea that the game's theme is horror, and you can't really do that with goofy skeletons throwing bones, but you can do that with something that's out of the players control, which is exactly what the day and night element does.
Symphony of the Night was the same god damned game, y'all love it so much...
Same with Zelda 2. It's really no more cryptic than it's predecessor, and it has the benefit of trying a different play style, not being a carbon copy hastily shat out riding the profit waves of the first Zelda. It's combat was interesting, it's use of magic hasn't been seen in any Zelda since, nor has it's basic rpg elements. It's actually pretty close to what Symphony of the Night became. I'm upset that they never explored this style of gameplay again in a Zelda game. Imagine it, Link's Smash Bros controls which work perfectly in a 2-D landscape, puzzle solving, RPG elements, coupled with modern day fundamentals like a map, and better clues on what to do, it would be great!
And I'm sorry, you're absolutely wrong about Mario 2. In no way is it inferior to it's predecessor. Mario 1 will always remain a classic and a masterpiece, but Mario 2 had the exact same fundamentals set in a more interesting world, with way more stuff going on. Also, it's worth noting, remember the time when this came out. We in the western world had no idea Doki Doki Panic or The Lost Levels were ever a thing, so to us Mario 2 was the only direct sequel. This shit blew our minds when we were kids. It was weird, interesting, there were new and different mechanics, every character was unique and distinguishable, even the idea that Peach and Toad became playable characters was great. Plus, this game introduced several characters that would later become Mario canon, the shy-guys, ninji, bob-ombs, Birdo to name a few.
All of these games are a little rough around the edges, but none of them are truly inferior to their predecessors. I think even to go back into the past and foster this idea that if a sequel isn't EXACTLY like the original AND better than it's immediately worse than what came before it is incredibly shallow, and exactly why we get a new Assassin's Creed and COD every 5 months. God forbid anyone try anything different, even in the past.