Have only read OP, but I can't help feeling this is another one of those threads where people single out parents because they're an easy target.
I have a Maclaren, a 'sensible'-sized buggy. I hate large buggies (though the all-terrain ones are damned useful if you want to burn off your preg fat by running...). However, all the things the OP was whingeing about I have seen done by people without buggies.
So it seems to me that it's not buggies that are the problem, it's people getting in your way. Which, frankly, is just life, innit?
Smurfgirl, I am at your claim to be fed up with being "barged" out of the way by people's buggies - do they actually ram into you, or are you using a little artistic exaggeration here?
If someone tuts at you because you politely ask them to move their buggy, it's not the having of the large buggy that's the problem, it's the person's attitude. And if someone's in front of you and blocking your way (with or without a buggy), just learn to say "excuse me". It's really not that hard.
So, yes, YABU. Because you're clearly just in a whingey mood.