Ya, but then she ended up with a bunch of useless spells. Theyre witches and wizards who can, what, fix broken eye glasses? Even then, they seem to just forget about most of the more useful ones! You can make ANYTHING float as you want! Why not do that ALL THE TIME? You can zoom around on a broom but you choose not to? I mean, maybe Ive missed a crucial plot point that prevented them from doing these things... but, yeah, thats why I was always disappointed with the magic in the show. 

I dont mind keeping most of the magics the same, but I wouldnt mind having the freedom to add certain spells. Also, shouldnt there be some kind of drawback to casting? If Im capable of whipping around fire at will, can I do that until I dont care to do it anymore? Will I ever get tired from casting? Etc. 

Also, something else that bothered me, at least during the movies, is the visuals of the spells. Eventually theyre just throwing around magic balls or beams. EDIT: Now that Im rereading your post, I guess the visuals dont bother me THAT much... practicality > flashy. I get it. 

Idk, Im okay with keeping the original spells but this might just be some food for thought.