I think you would be very surprised as to how many people ride things without paying for them, but I have no data to back this up. Where else can I ride a plane, bus, boat, train, gondola (I can think of only 2 free gondolas) just to "check it out" without paying for it? The issue I have is that I am paying for this, so why shouldn't they?
It is already a line item that I pay for as a Riviera DVC owner. Anyone who is a hotel guest along the gondolas or park guest is already paying for it as well as a line item. Guests at the Tokyo Disney resorts get a monorail pass. Source is the official Tokyo Disney site:
Convenient Monorail and Shuttle Bus Service for Free
A complimentary pass for the
Disney Resort Line monorail, which links the major areas of the Resort, is available for Guests staying at
Tokyo DisneySea Hotel MiraCosta or
Tokyo Disneyland Hotel. Guests who wish to use the monorail can request a pass at their Hotel or at the Hotel Service Counter on the station level of the Tokyo Disney Resort Welcome Center. Complimentary shuttle bus service aboard the
Disney Resort Cruiser is provided between the
Disney Ambassador Hotel and the Disney Parks.
https://www.tokyodisneyresort.jp/en/hotel/dh/privilege
Also, I believe you can walk instead of using the monorail in Tokyo, so that comparison will not work here as you cannot walk to AoA, Pop, Riviera, or CBR from the parks. If I could walk versus anything else, I am going to walk unless the weather is horrific.
Bottom line, I don't think people should be paying for the gondolas while others ride a mode of transportation for free. Let them pay like we do. That'll cut down on the crowds IMO. If you are staying at one of the resorts which the gondolas service or going to the parks, then you have paid for the right to ride the gondolas. If you aren't, then you need to pay for a pass. Whether it's a minimal number of people or a large number of people riding for free shouldn't matter. Everyone who rides should pay for it rather than only charging hotel and park guests.