I recently converted a basic Chase Freedom World Mastercard (set to points) to the Plus side (no change in purchase APR of fixed 10%) with the miles option. Even though Chase's website says that traded accounts aren't eligible for the $100/10,000pt/mi bonus, I made the attempt anyway (you never know what you can get unless you negotiate). Unfortunately, they have no trade space on that particular point. Oh well. The bonus was somewhat made up from using the Shop Rewards network of theirs (Overstock has an 8% or 8pt/mi per $1 till the end of June, for example, and they had some items of current interest).
Overall, the bills alone make the $30 annual rewards fee worth it over the course of a year. With no earning or redemption caps nor expirations, that does help. Effectively, I've already earned 2-3 free round-trip flights on the card, and it's only been a year since the account was opened.