It's pretty close to the release of the second, I wouldn't play it unless you can borrow it from a friend or maybe Redbox it or something. There isn't much story there that you need to know or anything.
You want a reason? I'll give you a reason: It will make you appreciate more the things that BL2 changes/adds. See mini-map, weapons being more visually distinct, voice-acted story, trade system, grenade mods with multiple capabilities, etc.
If you haven't finished it at least once and can get ahold of it for cheap or free, I'd say yes... at least so you can get used to some of the basics that'll return and familiarize yourself with characters. If you have finished it... depends on if you've got the time or get burnt out too easily.