It's just the way plenty of footballers are, whatever we may think of it.
At the end of the day, he's a really good footballer who has never put less than a bloody good shift in for Villa, and who has sprinkled that with the occasional moments of magic. Yes, we 'gave him his chance', and he has taken it and then some. He hasn't complained, bitched about the club or manager. I'd say he's done enough to earn a shot at the very top level, and enough for us not to be too bitter about it.
It's no surprise at all that Man Utd are interested, and especially at something of a knockdown price; they'll be keen to know, as I am if I'm honest about it, if he really does have another level in him.