I dont think its disrespectful at all. You aren't saying, this country's better then yours, just because you fly it higher, or dont fly the second one at all, and i think people overrate the importance of the flag. You may be saying, this country is more personally important to me, but thats not being disrespectful, its just who you are, or even as some people have said here, they just think it looks cool. I personally dont fly a flag anywhere, but if i did, it would always be the Australian flag, wherever i was at the time, because it would always be who i was. This may just be cause of our culture, we dont put so much importance in the flag to recognise our nationality, and very few actually fly one, i just think flying a flag is more an expression of yourself, then a show of respect.
On the UK and st george thing, thats pretty messed up. If people want their culture respected and left alone, they need to do the same for everywhere else. Not quite the same, but in the shopping centre i work in, we weren't allowed to play any christmas carols, because people complained that it was offensive to them.