If Guido had just left division the way it worked in 2.7 we'd all have moved by now. Everything else the community is fine with, but it is enough of a sticking point for some people that they can't be bothered to make the switch.
I think you'll find alot of developers have very different pain points for the switch. For you, it's integer division. For me, it's unicode strings. Some people in this discussion even cite the print function.
Long story short, if you're turning something easy into something hard, don't expect people to switch.
