Only because it is the only album they ever produced and because they are, in fact, The Sex Pistols. Musically I don’t know what they were doing that others were not, especially The Ramones. Compared to The Clash, Television, the Talking Heads, and even DEVO their work taken out of a social context doesn’t really stand up.
The Ramones did the three-chord punk with more variety and The Clash did the revolution rock with more intelligence and style. The others I mentioned went on to conquer the 1980s for intelligent, artistic rock if you knew where to look.
Don’t get me wrong: I love The Sex Pistols. Their album was one of the first punk albums I bought and I still enjoy it. But it can be disappointing to someone who’s expecting musicianship or anything more than historical value.
To say something constructive for a change, look for ‘Blank Generation’ by Richard Hell and the Voidoids (fashion-spawning 80s punk), the New York Dolls’ self-titled album (a large influence on the Ramones), and Minor Threat’s Complete Discography (the song ‘Straight Edge’ alone is worth it for the revolution angle, but it’s really surprisingly sensitive and responsible hardcore punk).
(For revolution alone, though, early Elvis is damned near unbeatable. There is a reason he had a huge and rabid fan base even into his bloated, self-destructive late period. ‘Jailhouse Rock’ and ‘(You Ain’t Nothin’ But A) Hound Dog’ symbolized a reborn youth culture that would come to supplant the great Lost Generation of Hemingway and Fitzgerald in long-term influence and social change.)