With all due respect, I totally disagree. Firstly, loyalty in their eyes IS the size of the membership; if you have 500-1000 points and make 3 trips a year and spend a lot of money, you ARE more loyal. Also, rewarding members based on length of membership is counter-productive b/c no amount of money can add to the length of any membership; they want to SELL something, so what would they sell? I can't spend money to be a 20 year member.
Also, there are people who have been members for 1,2,5 years who spend a fortune on 2-3 trips and 500-1000 points. They would take great umbrage with the notion that they are less loyal b/c they were in high school in 1991 and weren't yet a
DVC member.
To Disney, loyalty IS the size of the membership. The more you add on, the more loyal you are. A tier system cannot arbitrarily dismiss members based on purchase year, but can subjectively classify them based on points; nobody will be offended. You want to be in the "upper tier"? Buy more points!
The million dollar question is, what will this "upper tier" provide by way of perks, and will it be enough to warrant spending the extra money?