I think I take more issue with the way you present your info. You make it sound as if iTunes hardly works on a PC and obviously, that's not true. I know tons of people that use iTunes and it works prefectly fine, just like I know lots of people who use Macs and have issues with iTunes. That doesn't mean I'm gonna run around telling people that iTunes is buggy on a Mac. Sure, you can go to iLounge and see people who have problems, but what else would you expect to see? "iTunes works flawlessly on my PC...just giving everyone a heads up"? No, people go to forums like that when they have problems, so saying that since PC people over there have problems, therefore the software is buggy, is quite skewed. I mean, if you want, I can go pull some threads about people having issues with their Macs...and I'm sure you know, the pool to pull from is quite large.
Each person's PC is different and iTunes might conflict with other software (this goes for a Mac too). Personally, I've had very minimal issues with my PC that I've had for 6 years or so (upgraded as needed). It's on 24/7 and I've gotten 1, yes 1 virus in those 6 years. If you want to take a quote from Apple...my PC, it just works.
To address your last statement...of course it will work slightly better on a Mac. It's apple software on an apple computer. But the vast, vast majority of people will no issues with iTunes on their PC. Why would Apple release software for a PC that doesn't work?