It's not a deal breaker to me. I played a fair amount of hours of Torna and Xeno 2 on portable mode and while the drop in visual quality was quite noticeable, it never affected my overall experience.
That being said, given that there are other more demanding games on the system with equal or better resolutions and that in the end this is a remaster/remake of a Wii game, it should definetely run a lot better than it does. If I could choose, I would obviously ask for a patch to improve resolution.
So... not the end of the world, but I rather have the issue fixed.