I don't buy into the accidental backspaces so much (when typing at least, though perhaps understandable for gaming). 'A' is a home position key where your hand should be sitting comfortably and ready to press the key beneath it with familiarity. Do you hit ' (apostrophe) by mistake when typing ; (semicolon)? That would be the equivalent on the other side of the keyboard.
I also don't see why it would encourage sloppy typing, particularly since you have all of the Colemak typists who would probably want to disagree with you. About breaking the motion, that seems very subjective (which of course at the same time means you're entitled to that opinion). I'd rather my typing not be so broken by having to move so far to press backspace and instead only have a small hiccup.
In WoW I can see that being true in terms of frequency, but as backspace probably accounts for 3% of keypresses (estimating typing accuracy at 97% based on
http://www.keyhero.com/ and this actually tends to increase as you get faster which can easily be seen by looking at the accuracy of the people on the leaderboards at typeracer), that would make it around the 13th most commonly pressed key after spacebar and etaoinshrdl, which almost makes it home row worthy, so much so that it would probably be well received switching places with apostrophe. Actually, this makes me think that apostrophe would make a good position for a 1 unit control key, because it would be opposite of ASZXCVF which are commonly used with control so that you aren't doing combos with the same hand.
And yes, while control key usage does depend on use cases, programming is not a typical use case when considering typists in general (as programmers represent a small portion of people who type), and even programmers will type a fair amount of plain text (either on or outside the job).
