It's terribly impractical to use arrow keys unless you operate the mouse with your left hand. Using WASD is superior in the sense that every (common) hotkey is within a reasonable distance and is much more accessible than keys adjacent (if you could even consider them adjacent) to the arrow keys
As a matter of fact, almost all computer games are based around WASD movement. There are a few zany games such as Happy Wheels that (I think) use arrow keys instead.
I keep my left hand hand like:
World of Warcraft was the first real PC game I played, so that probably had a significant impact on how I moved (keybinders ftw!).
It ultimately breaks down to muscle memory; if you're capable of hitting the adjacent keys while moving using arrows simultaneously, more power to you.
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Edit: Doh, just remembered not all keyboards are layed out in the same fashion as those found in the U.S. Even with that in consideration, I think my idea still stands.
I rate it 3 memes.