A couple of thoughts from someone who has only ever used CC to trade a few vouchers but who would be worse off if it did not reappear:

1. Gift cards = cash (especially as you can sell most gift cards on ebay for 90%+ of face), cash = selling something, selling something = going against the spirit of CC and indeed the T&C's of all airline and hotel programmes. It should be stopped.

2. Perhaps the entry requirements need to be tightend up, although the '90 days' rule is helpful and cannot be abused by post padding

3. It is difficult to put a value on what is 'fair' in terms of a trade. I'm in Basel next week and the only major chain is a hugely expensive Hilton. Its a city where I would potentially have traded a disproportionate number of other points (say 60k Priority Club) in return for 30k Hilton - others may have seen the trade as unfair to me but actually it would have been perfect in that scenario. It is also relatively easy for a newcomer to CC to search for similar trades to get a view of what is and is not reasonable.

4. There should be a rule that there should no third parties involved in any trade. If I do a deal with you to book a hotel room for you, it must be for you - I don't want to be booking for a random third person I don't know because the other side of the trade has resold my offer of a room for something else.

But CC should remain in some form, if only for people to give away stuff they don't need.