One of the reasons I said the theme park comparison wasn't entirely 1:1 was, for example, the recent "Little Lady's Day" event. For roughly 30 minutes or less of effort, the game gives you vouchers for a 5 piece exclusive outfit and an emote. No cash shop tie-in or special extra purchases necessary outside of the game and subscription fee. Gettin' some free souvenirs there, but I guess maybe that could be tied into a limited time special or something.
Now, I see the kerfluffle are certain things like that /playdead emote where instead of there being an event for these, they were put straight into the shop. But I feel like the chicken/egg question with those is whether or not the devs would have created these straight-to-cash-shop items if there hadn't been a cash-shop to monetize the production time put into making them. We haven't suddenly stopped getting new outfits and emotes handed out to us for free* (*game price and subscription, yadda yadda), we still get those, in addition to these straight-to-shop items that I'm unsure if you can really prove whether these items would even have been created if SE had not plopped the cash shop down on the game.
Basically, you still get the same complimentary breakfast at the hotel, but now the hotel offers the option of a premium breakfast room service options for an additional fee.
Edit:
While I understand you want to just pay everything up front; not everyone cares about the extra items in the shop, so it would potentially cause a drop in subs if people saw their subscription fee go up for the sake of items they weren't even interested in to begin with.
Maybe they could introduce a premium subscription option for those who are interested in getting those additional items tied in without feeling nickel and dimed.