I agree with the SPG promoters for two reasons: one mentioned already and one not.
1. Fees. Although Randy discounts fees, I think they matter. For example, if it takes you one year to charge enough for a trip, that "free" trip could cost $50-$150. The Amex SPG makes the trip really free.
2. The ability to "flush" orphan miles. I have read many threads suggesting to get rid of orphan miles by reducing balances (e.g., buying magazines, using Milepoint.com). But by reducing balances, you usually get a redemption rate of 2 cents/mile or less.
With SPG, you can top off nearly any account and get three benefits:
a. Clear out the account
b. Get a good redemption rate, and
c. Not have to worry about finding obscure ways to get rid of the miles.
The only SPG drawback is that you have to get a Visa/MC since Amex isn't accepted everywhere.