Silver's not entirely worthless. I'm a career bottom dweller in the elite ranks, and having bottom tier has been far better than no status for me. Yeah, you're mostly not getting upgraded (but you might on a leisure trip on a Saturday, like the time the 3 of us got upgraded on PWM-LGA-MCO to Disney World). The real benefits come in predictability - you use the short line to check your bag, board, and if you need to get someone on the phone you wait less. It's also helpful when you're booking with your family for one of you to have status, since quite often when we book at least, the only 3 seats together are the paid seats closer up front.
I wouldn't spend a ton of money for silver, and maybe say not at all if someone else you book and travel with already has status, but it is very much better than nothing and I'd probably spend a couple hundred bucks for it.