The expenses for the SPA do not come out of your dues - you are NOT paying a penny for that facility unless you choose to use the personal service. The same goes for restaurants - they don't cost the members anything unless they choose to use them. Barbershops, Beauty Salons, Boutiques and boats are available at many resorts, but none are included in the membership expense or reservation expense - they are all funded on a fee-for-service basis.
The childcare facility (Harbour Club) at BWV/BWI has closed - I suspect due to insufficient use to justify the operational expense - but guests may still use the other onsite centers. While many of the DVC resorts do have some free recreational activities, most of the programs also have an expense involved (often with a discount for DVC members).
We've stayed in very few timeshares where there is any childcare service provided - other than a list of local babysitters. The few that have offered some form of childcare have also had a fee schedule for those desiring the service. WDW and DVC guests have at least as many childcare options as most other timeshare resorts and many other resorts in general.
Thanks for the clarification. The spa was a bad example. How much would you guess the dues increase would be to cover something like this?