The #1 obession has not only grown here, but in the industry among popstars. Right now, female pop stars are snatching up #1's like it was the early 90's. And while they don't really determine whether an act is more or less successful than another, it brings postive press that just cannot be bought - particularly if you're "breaking records".
Take "Blow" vs. "Hold It Aganist Me"
I guarntee you someone that's musical knowledge doesn't extend past PerezHilton.com (95% of the public, if not higher), believes the later is the bigger success. Why is it important for people to believe you're a bigger success? People buy what they believe is popular or cool. Songs that have slower/steadier/smaller-peak runs don't get press.