Why shoot BBs?

I just bought a Crosman CR357 "revolver" that shoots both pellets and BBs. Why would I ever want to shoot the latter? They may be cheaper than pellets, but pellets are not expensive. Wouldn't the steel BBs wear down the rifling and be less accurate? I just can't figure out why they even include a clip for such poor ammo.
 
"T3PRanch"I don't think you will find ANY rifled BB shooters. I know the gun your referenced is a SMOOTH bore. :)

Thurmond
According to the manufacturer the CR357 he referenced had a rifled barrel.
The current Crosman SNR357 revolver does has a smooth bore like you mentioned.

Daisy Powerline 880 and Crosman 760 Pumpmaster both have rifled barrels, and shoot BB's.

The latter two have scant rifling to reduce likelihood of BB's getting jammed.
I rebarreled my 880 for this reason with an HW blank. Did this because the CP pellets would often slide out of the barrel if aimed downwards, even though CP's are on the fat side. Had never even shot BB's out of that gun prior to that. Made a moderated bullpup out of that 880 back in 1997. Still own it.

To the OP's point: I'd agree steel won't be kind on rifling, but versatility is the aim I reckon, and bulk BB's are dirt cheap... until they ricochet. It does seem ironic when a CO2 gun (costly air source) is engineered to shoot frugal ammo.

Playing "Devil's Advocate"...
Little semi-auto CO2 BB guns are a hoot and cheaper to produce in reliable form with BB's being a lot easier to auto-load.