Perhaps we need to ask the exchange companies to make it clear what is included in an exchange, and what is not. If there is an onsite pool, ut there is a charge to use it, don't count it as a resort amenity. It is a commercial amenity that happens to be onsite.
I see it as three different types of fees:
1 - pass along fees. The resort thinks the maintenance fees are too high, and to keep them low removes certain items from the fees. They then charge those that use those services. Of these fees, the ones I have the least issue with are those for services that truly are optional. This would include mid-week maid service (not just tidy), certain activities & materials for those activities, A/C if there is a reasonable alternative.
2 - mandatory pass along fees. These a fees you can't avoid, but are charged to anyone who uses the unit. This would include certain utility fees, Access to amenities like the onsite pool or fitness center. These should be included in the maintenance fees, but are not. I prefer to avoid these resorts, but at least they don't treat exchangers a second class citizens. Some resorts may do this because their structure doesn't allow them to differentiate different fees among their owners - but in that case they should include a base fee in the maintenance and a surcharge only for those weeks that actually cost more. Owners who use their week should be against this system, because it actually costs them more - weeks that go unused don't result in a fee paid at all!
3 - exchange only fees - like what DVC charges. These fees are, in effect, paid twice. Since owners are not charged extra it is assumed the expense is included in their maintenance fees, so has already been paid before the exchange. Some would argue that the services are provided as part of a membership that is distinct from the ownership. If that is true, I would expect the owner to get the benefit whether they use their week or not. In such a case, I could go to my home resort and use the fitness facility whenever I want while the person using my unit can't without paying a weekly membership fee.
But this goes against the basic premise of TS exchange - the exchanger is not getting full benefit of the use of my week. This is particularly true if my guest isn't charged but the exchanger is - because by not charging a guest the resort management is acknowledging that the benefit IS part of my ownership. Do you suppose DVC would allow you to sell your membership but retain the right to use some of the benefits?
RCI took a stand several years ago, and told DVC they could not charge the $95 fee, and DVC moved to II. That's where we find Marriott now too. If RCI had not taken a stand, who knows where we would be now. Perhaps some day we will get to a point where the only thing we exchange is the right to "rent" a week at a discounted price. I will pay $10 membership fee each year to my home resort. If I use my week, I will pay the cost of maintaining it for that week. If I exchange it, whoever uses it will pay that fee.