It could be beneficial and would also stop crew not showing up for certain flights because they are "charity trips" and not worth coming in to work for. Crew "not doing Indians" because they're not worth anything or the LAD (5 no show's on my last trip there a couple of weeks ago - coincidence?). BA will never agree to bidding system under excisting terms and conditions.
VS does it and also allows crew to swap trips online as long as they are keeping an eye on their 900 hours. If they are out of hours after six months for swapping to far too many longer trips it's their own fault. LH also does it but they are also on different terms and conditions.