Also, I do not doubt Battletoads is easy for you. But know that you are an absolute outlier and the game is quite difficult for most people. Generally people can't pass the Turbo Tunnel (which honestly is not hard at all).
I could beat NG as a kid. I can beat it now. Yes it's tough, but it's manageable. NG is the quintessential "git gud" game to me. The controls do what I want. If I learn the level and the patterns, I have the tools to execute.
That said: I still can not beat Battletoads. Now of course it's all subjective, but: The controls aren't as crisp as they should be. Nothing is quite as balanced as it needs to be. The constantly shifting focus and changing rules from level to level adds variety, true, but also punishes you for not knowing what the fuck you're doing right away. There are some really poorly designed areas and awful gotcha moments, and there's quite a bit or RNG involved in some of the shitty spots as well (swimming around in Terra Tubes is total horse shit due to the randomness of the enemies). NG doesn't have anything nearly as punishing as Clinger Wingers, and for me, that's including the final stage and having to go back if you die. But even if you do? You can try as many times as you want and you don't have to play all the other hard bullshit before it again unless you reset the game.
TLDR: My opinion is: NG's legendary difficulty is largely because of a glitch and in one unfortunate spot at the end of the game, but at least you have unlimited continues. Battletoads is mostly a repeated kick to the crotch, the only difference from level to level is how hard it's kicking you, and it kicks mercilessly until your dead for good.