While this is PURE SPECULATION on my part, here's an educated idea on why the games you're claiming that "must" be in the list were left out...
1) Character Obscurity / Series Confusion -- Donkey Kong (Jr.) is well-known character that the general public can quickly recognize. Diddy Kong was introduced in DKC & it still relatively obscure in the whole SNES games, which can confuse the general public (not the critics & seasoned gamers) if they included a game that includes the Donkey Kong name WITHOUT Donkey Kong himself.
2) Licensing & Genre Saturation -- as RPG's comprise 20% of the game list with two pure Square Enix games + the Nintendo colab (SMRPG)... there's not much room on the list for more RPG's.
3) Licensing -- The game was originally made by LucasArts, which their Interactive (games) division was killed shortly before getting taken over by Disney... which makes things a bit difficult for the age (assuming the IP rights were retained by LucasArts).
4) General Public Obscurity -- While it does have some merits with critics, it's not a well-known title for the general public & it a bit difficult (being a simulation).
5) Licensing issues galore -- Need to secure the rights of all NBA logos AND player's likenesses for a re-release... which makes it very difficult & costly to properly secure everything.
6) Title Obscurity -- Kirby Superstar is more well-known on the SNES than the "Dreamland series" of games & has a higher "gameplay value" over Kirby Dreamland 3 that gives it more appeal.
7) Brand confusion / Licensing Issue -- While it was called "Tetris Attack" in North America, it was called "Panel de Pon" in Japan that didn't have the "Tetris" brand NOR the Yoshi Island themes. The game was also re-released as "Pokémon Puzzle League" (Same game, just with Pokémon Themes) on the N64 (& GBC) & "Puzzle Planet League" (without any theme) on the DS.
The owners of the Tetris brand, prior to the creation of The Tetris Company, have publicly stated their regret to allow Nintendo to call the game "Tetris Attack"... which practically kills any official re-releases for the SNES version in the US.
This is just my 0.02 MB here... Hope it sheds some light on the subject.