Considering that for adults the discounted AP is less than your 10 day MYW no expiration hopper pass, why would you not buy the AP. Even if you don't use it again during the next 365 days you still save some on each ticket.
If you can use it again before it expires you are saving huge amounts over MYW tickets. Even if we only go once a year we do stagger our trips so that our last day of the second trip is the day our tickets expire.
If you are buying any MYW base ticket over 5 days with hopper and non expiring, you are paying more than the AP with
DVC discount.
However if you are saying you only go to Disney for 4-5 days each trip and those trips are spaced further apart than 365 days; then no the AP won't work for you.
But I imagine you are not the norm for most DVC and most are going much more often in 365 days, hence the reason to discount an AP for them. We go for 2 weeks each trip and each trip is within the 365 days so for us it is a huge savings and we were thrilled to get it.
Also many times due to having tickets we will throw in a 5 day unplanned stay in between.