I have to agree that for some cruises, using DVC points is "expensive". In our case, we had a number of points we needed to use and my DD18 and DS21 weren't able to stick to our original plans for a family vacation. Cruising the canal is something my DH has always wanted to do.
We are using 748 points for 2 adults in a Cat 6 guaranteed. Our original Cat 9 is a better value per point, but this DW really wanted to be able to step outside our stateroom on a 14 night cruise (picky, picky, picky). Let me show you some numbers

. BTW, this is our first
Disney cruise so CC doesn't apply to us. From what I've seen, current DVC point rentals are typically $10 to $11 per point.
Cat 9 - 2 adults: 532 DVC points or listed rate of $6240.50. That's $11.73 per point.
Cat 7 - 2 adults: 684 DVC points or listed rate of $7440.50. That's $10.88 per point.
Cat 4 - 2 adults: 910 DVC points or listed rate of $8840.50. That's $9.71 per point.
It looks like the Disney Collection trade is a better value for the higher category staterooms. I've done a sniff check of other cruises and the trades weren't very good. So you've got to look at both the cruise you want and the stateroom category to see if the trade is worth it.
There is a $75 transaction fee for the cruise booking. Yeah, this was paid in cash, but since it is DVC fee, I wasn't considering this as cruise rate. Just another DVC fee... There's also annual maintenance fees and taxes. On the other hand, the DVC membership lasts for many years.
Every DVC member has different reasons for purchasing. In our case, we were going to DW about every 18 months since my son was 15 months old (he's 21 now). My husband and I even got married there 7 years ago

- a very beautiful small wedding. We've used our DVC membership at WDW and traded for a fantastic Hawaii vacation 2 years ago (Concierge collection). We've been happy with our DVC membership, but everyone should look at their own circumstances.
BTW, it looks like more staterooms categories are available today at the
DCL site.