First of all, apart from both being cartoony Battletoads and Cuphead don't look anything alike. Also, even if the game had the exact same artstyle as Cuphead I'd still say it looks like a generic beat'em up with close to no platforming elements which are what I like so much about the NES game.
They announced it has multiple genres in it including platforming in the trailer.
Here's the list below..
^I bolded what can be a genre while the unbolded is more what you can do in the game.
No it really cant...
Cuphead emolates the retro cartoon feeling and pulls it off amazingly.
plus its gameplay works as it is.
Battletoads looks like a cheap flash game.... and the gameplay looks "off" to say it mildly, it doesnt even feel like a battletoads game.
Its a "night & day" differnce between the two.
You might think they both are aiming for the same thing, but the differnce is how well they pull it off then.
Like theres clearly a massive quality differnce between the two.
Battletoads did not get anywhere near the Tender love & care (tlc) of Cuphead.... and it shows.
Both Cuphead and Battletoads are hand drawn and looking at the two picks I posted before, its funny to read people say one looks like garbage and the other looks great. They both look like well drawn games. I think you are more disappointed that you don't accept the look of the Battletoads rather than it being drawn good or bad.
To me Battletoads looks like a cheaply rushed cartoon while Cuphead looks and feels like a piece of art with so much more work put into it.