I also think Spelunky classic was the best version of his series on account that the aesthetics and soundtrack were so banger.
That's why I wanted to preface everything before I made this statement. Spelunky 2 is one of the "worst" games I have ever played. I mean this in a very nice way. However, I consider it incredibly disrespectful to the players.
In order to see the "true" ending of the game you have to do an insane number of really esoteric tasks to get to what is called The Cosmic ocean. And, in this Cosmic ocean you then spend 99 levels working in what is arguably arbitrary hell to complete it so that you can finally "beat" game.
What I find so disrespectful about Spelunky 2 is that the experience is frustrating as hell. And, that's intentional. He has designed the game in order to elicit that response, but that doesn't mean that's necessarily a good thing
And in one of his axes he lists broad appeal, however there is no way any person in the general population can even remotely approach the skill level required in order to enjoy this aspect of the game. And, some people might say "get good", or "you need to learn to play the game", but I don't find that to be a sufficient explanation or sympathetic response to those who really do enjoy the game, but are locked out of really interesting parts of it based on tedium that requires incredibly long playthroughs that require incredibly difficult tasks to be achieved in order to see it.
And, I get it as a designer he made the choice that this is how the game should be played, but I cannot really ever get over how the game has changed between Spelunky classic versus Spelunky 1 versus Spelunky 2. And, how much he made a point to enforce that experience through design decisions.
I'd also like to touch on the fact that each following iteration changed from interesting to an art style that felt more like McDonald's art instead of sticking close and cute like the original Sprite art that was created.
I have put so many hours into Spelunky and it's crazy because I would expect to have nice things to say about a game that I spent so much time playing, but for me I really wouldn't suggest Spelunky to anyone because of the design decisions from Derek Yu. In fact, it's my top choice for games that get in the way of themself to the detriment of the player.
So I guess all of this rambling is to articulate that Derek Yu does know some things, and he has been successful, but I don't consider his opinions to be very valid regarding what makes a good game for the general audience.