As for renting: it's a modest amount of work. You can market it yourself (e.g. on the DISboards Rent/Trade section), or there are a few services that act as matchmaker for you.
More broadly, there are definitely two components to any timeshare purchase: it's a financial decision, and a lifestyle decision.
All things considered, my guess is that most people ultimately spend *more* on vacation lodging once they are timeshare owners rather than less, compared to "life without timeshare". I think we probably do. Sure, if you only buy as many points as you'd need to stay in studio units for exactly as many nights as you spend in Disney's hotels right now, on a long-term average basis, it actually *is* cheaper. But, most people don't do that. They go a little more often, or they decide that really, studios aren't much fun, and villas are much nicer, and so on.
At the same time, if you add up all the costs in a timeshare, and compare it to what you could have rented the same number of nights in the same style of lodging conventionally, you are "saving money." It's very similar to the dining plan. Most families, left to their own devices, probably would not spend quite as much money eating in Disney parks and restaurants as the appropriate dining plan costs. But, as long as you use all of your entitlements, you are "saving money" vs. what the same food would have cost on menu prices.
So, the decision comes down to one of lifestyle---do you want to vacation more, in more spacious lodging? If so, timeshare can be a way to do that with reasonable costs. You put it right when you say "get your money's worth". You aren't necessarily saving money, but you are probably getting decent value.
The only part where I disagree---at least a little---is the idea of doing this for my kids post-adulthood. Lodging is only a small component of the cost of a typical vacation. You have to get there. You have to take the time off of work. You have to pay for food, and probably entertainment too. I don't know about you, but when I was getting started, you could have given me lodging at WDW for free, and I still would have had a hard time taking a vacation there---at first because I didn't have much money, and later because I didn't have much time.