I think it only makes sense if you need to meet a spending threshold you wouldn't already meet on the credit card, and meeting that threshold is fairly beneficial. For example, if you had the BA card and did not spend enough normally on it to meet the $30,000 companion pass threshold, it could be worth it to put all or some of the cost on the card if you are able to use the miles you receive and companion pass effectively. Most other bonus thresholds (like status with certain cards like the Hilton or SPG) is probably not worth the premium, in my opinion. If you are not trying to meet a threshold, spending 3 cents per mile is not cost effective, you can buy miles directly for cheaper (and if you aren't doing that already, then this is not worth it).