I never preferred WSAD for gaming. Nostromo, FTW. Why occupy four fingers for movement when you could just use your thumb on the D-Pad and leave your other four fingers free for other stuff. It's much better, IMO.
How do you jump while moving? You can't use your thumb on the D-pad and the big space button at the same time. This is the one really dumb thing about the Nostromo. Do you remap jump to a different key?
Back on topic, I think WASD evolved because of lack of n-key rollover on most modern keyboards. The only way to increase the likelihood of key combos working is to use modifier keys to do commonly used functions (run, crouch, etc) because all keyboard matrices are designed to use those in combination with other keys. This also ties in with the USB '6 keys plus modifiers' limit.
So if you are forced to use the Ctrl key, your hand is forced way over to the left of the keyboard, making WASD the most comfortable choice.
Personally, I use RDFG for movement. The number of keys within easy reach is
huge. As a bonus you get the locator nub on the key under your middle finger. But I only did that because I map them to my Nostromo, lol. If I had tried to use that system on a non-n-key-rollover standard keyboard I would have had issues. Thankfully I now have NKRO boards so it won't be a problem.