The following legacy mods in WhyNot feel like cheating and, I think, should be considered for removal. Even if it breaks compabitility.
flyingcarpet : has no restrictions to flying. Unlike the supercub and hydroplane, it does not require fuel. It's also less expensive to build (wool, mese and gold versus diamond, wool and tin, and multi-step for cockpit and wings).
subspace walker : lets players see through and pass through walls and stone. It could maybe be an endgame item that's very difficult to craft (ex. obsidian, diamond blocks, multi-step). On the other hand, it doesn't seem to work for me anymore... The logs show "singleplayer activates subspacewalker:walker" but nothing happens.
The following legacy mods in WhyNot feel like cheating and, I think, should be considered for removal. Even if it breaks compabitility.