This is a great question!!!!
It sounds like DVC's main point is for wanting "deluxe" accomodations.
If you are someone who likes moderate's just fine, this may not be a good deal. Let's look at the math another way:
We stay for 8 nights at CSR: $2622.00 which includes park hopper tickets for 4 at a cost of roughly $1000, so for rounding purposes lets say the actual room charges are $1622.00.
Now, if I was a DVCer (remember not concerned about mod. vs. del. as I am perfectly content in a mod. and this is what we're trying to establish this at), I would pay $600 a year MF. So, now the extra charges, a regular person pays is $1022. For 17 years I can pay this fee before my initial 17K investment fee starts to matter.