This is all great advice. While it is very true that you can't make them do it, the best thing (IMO) to do to make them WANT to do it is to start out, then reward the players who DID do backgrounds with a 'background-involved run' -- I find that doing that one out of three runs is just about the sweet spot, spread across those who have backgrounds. They get the crap kicked out of them, maybe -- but they also get a great contact out of it, or a particularly cool or unique item (gun, knife, sword, whatever), something to that effect.
Another thing is to point out how terribly, terribly easy it is to make a good background. "Start with normal life. Twist A: how you got your gear / first displayed your magic. Logical progression of that. Twist B: how you entered the shadows. Logical progression from that. And here you are." Give you an example or two:
Ladybird is a bioware-heavy street samurai, very subtle work, with a bit of cyber. The enormous amount of its cost was paid for by Evo when they picked her up after she placed 2nd in a marksmanship competition in Texas in 2066 when she was 16. She did lots of bodyguard and security work, and started to get into the semi-shady 'Company Man' side of the business in 2075, but clashed a lot with her desk-jockey boss at that point, so when an 'action' went bad and the rest of her squad was killed, she took the opportunity to vanish into the shadows, where she could be her own damn boss.
Jenga is a technomancer with a particular taste for construction drones of all things. Since they're practically everywhere, he's made a specialization of hacking them and using them in crazy-dangerous manners -- from creating holes in buildings with bulldozers to knocking chasing bikers off the highway with an excavator arm. Jenga grew up a corp brat, but since his parents were sanitation workers, not a very valued one -- MCT 'primary tier' housing was their lot, so moving from it to the Barrens wasn't so much a step down as it was a step over. Why'd he go? Well. Budding technomancer, hears talk about the experiments MCT does on them -- why do you think??
Then show them how this sort of thing can really make a character. I do not at the moment have access to the paizo.com boards (when I do, I'll edit this), but a great background can turn 'yawn, it has all the technicals in place, whatever' into 'that is the f*cking coolest thing ever, and I want this character -- and player -- in my game.'