The reason I suggest the change is that the current functionality is broken. Shift Key is required for casting spells which aren't on macro slots (which, to me, is anything with a long enough duration). It's also used for picking up an entire stack of items, or for typing capital letters, or whispering people/your group/your clan/your subpath.
Either "shift + arrow keys to scroll chat" needs to change, or *all* of that needs to change. I went with the simpler solution.
There can still be a way to scroll the chat with the arrow keys. Maybe they could use PageUp and PageDown (which is what they were meant for) instead. Right now, though, the game's controls have a very glaring flaw which needs to be fixed.