I've been thinking about it a bit, and I think it's probably ok for game developers not to think too hard about us left-handers in their game designs. They have to design their games somehow, and given how keyboards are laid out it's not like it's going to be that easy to come up with adequate keymaps for mouse-on-the-left people (I wonder if there are any mirror-image keyboards out there (except for the arrow keys, obviously) and if adjusting to them would be hard). The world is not about me and my odd genetics (I think my handedness is probably genetic; IIRC, my father is one of those rare truly ambidextrous people and I am not very handed); there are some things I'd prefer to have organised the other way around (inner coat pockets and scissors, certainly), but making everything symmetrical just makes it worse for the very common-case of righthanders.
So long as society is good enough not to persecute lefties, and remembers that we're around (and doesn't get too grumbly when we move mice and keyboards around in computer labs), I'm good. The existence of left-handed tools is just bonus.
I'm really not opposed to norms, even if they don't make sense for my particulars, provided they're mostly recognising the common case. If someone sets silverware for me as if I were right-handed, being offended would be kind of silly.