This exactly. It's the highest form of hubris to mistakenly think that someone else being different means they are inferior.
It's also pretty arrogant to proudly announce that you have unbound your S-key, implying that anyone who hasn't is somehow not as competent as you.
Truthfully, at the level we play, I don't have enough abilities to fill out my standard 1-5 and alt-1-5 keys, so I certainly don't -need- the extra key. Typically I use 1-5, alt-1-5, alt-Q for trinket, alt-E for whatever my character's other CC is (Quaking Palm on pandas for example), shift-F and shift-G for their primary class abilities (stealth and shadowmeld on rogues, stances on warriors, hunter's mark on hunters (before they changed that BS), believe me that is PLENTY of keys for a level 20.
When you have been playing PC video games, platformers, 1st-person shooters, etc as long as I have, you're not going to unbind one key for one game and throw off years of habit just to be able to say on a message board that you're one of the cool kids. If I were feeling arrogant myself, I could even turn it on its head and say that those who DO unbind their S-key obviously have no gaming experience outside of World of Warcraft PVP. But that is certainly not an argument I'm going to get into because I'm not that kind of arrogant (or masochistic).
Edit: AND I still have Q and E bound to strafe, for those times when I really need to strafe and I don't have the right mouse button down! AND I still have the arrow keys bound, for when I need to move somewhere but I'm eating chips and salsa with my left hand! (I'm left-handed in case you didn't know) ANNNND I play with a trackball instead of a mouse!! OMG burn Kincaide at the stake for being different *froth*