I don't think it's that healing magic doesn't exist

That is completely unrelated to what I said. Just, it's something Noelle would want, and she gets it there. I never brought that up whether or not it physically exists, however, it probably doesn't, considering that the game also implies Toriel doesn't have fire magic. It seems magic as a whole isn't a thing in the Light World.

And Berdly isn't any cooler than normal, he just has a piece of cyber themed armor and a lense.

I feel like going from this to this counts as "becoming cooler". It's not like it would change their personalities, they are still obviously themselves. They don't become different people, they get different things that they would want in their ideal, fantasy versions of themselves.