I would say that it only makes sense to cancel if you think there is no reason in the foreseeable future that you would use this. To me, it is extremely helpful for qualification - I have clocked in 5,000 PQPs this year and anticipate that going forward it will continue to contribute meaningful amounts of PQPs if I concentrate all my non-dining/travel/Freedom rotating category spend on it. But once you let it go, you can't get it back, and I see no world where UA issues a new card that comes close to allowing for such a high threshold of PQPs (10k) in the future.