One problem....airline tickets are non-transferable, they can only be used by the person named. Some airlines may allow you to pay to name change on a 'revenue' ticket, but as far as I'm aware never for redemption bookings using airmiles.
I work for Air New Zealand and a coupla years ago we changed the rules for airmiles. on our scheme you can use miles like cash to pay for any flight anytime, there are still airmile specials at lower rates, but these are strictly limited. This reduced the balance of airmiles held by Air NZ by millions, and gave a lot more people the chance to use up some points. As for the future, maybe some of our customers will be able to use airmiles to redeem for other gifts, but legally it's a bit problematic....
Same for charities, the idea came up here, but NZ's tax laws apparantly made it a nogo unfortunately.