If we consider it lucky enough that GTA materialised out of a glitch in another game, think it equally lucky that Rockstar - or as they were known then, DMA Design - played the PR game perfectly by enlisting controversial PR guru Max Clifford to help essentially big-up the game's more contentious aspects. GTA creator Mike Dailly stated, "He designed all the outcry, which pretty much guaranteed MPs would get involved...He'd do anything to keep the profile high."
Clifford's genius campaign involved getting stories planted in relevant newspapers - I think you know which ones - well aware that they would promptly spark a moral outrage among right-wing politicians and activist groups in particular.
The results, of course, speak for themselves. Amusingly, though, co-creator David Jones was quoted as saying they weren't going out of their way to make the game controversial, noting "We always did everything from the perspective of what's going to be the most fun. It just naturally kept pushing us down the darker direction." Even as a fan, this sounds pretty spurious to me.