Likely a ploy to see if they can siphon another boatload of money from the whales again. Some players in the spring event dropped hundreds or even thousands of dollars to acquire as many sets as possible. This is wonderful for the rest of us as it helps to keep the game running. However, the devs appear to have interpreted that as a cash piñata that they can toss out several times a year. Why else would this event offer not one, but two building sets in one event? Especially considering that 2 of 5 pieces of one are only from the wheel, with the entire second set coming exclusively from there.
Given the size of the new sets, I cannot see many people collecting multiple like the cherry blossom set. Also reducing desired prizes and total number of tickets was a low blow. Doing either would have caused players to become upset at the nerf, but both at the same time was a bad call. I don't care how infrequently desired prizes showed up on the wheel last year, I had way more tickets to burn knowing that I would eventually find a wheel with at least 4 of what I wanted. Not so this year...
Additionally, where is the corresponding increase in Reno and 1-up kit rewards? The set buildings from this event will bump us to 18 total set buildings, along with well over a dozen special event buildings over the past couple years. However, the kits to level them are still uncommon or rare. (I acknowledge that most people will only place a fraction of all these buildings, but even a single set can be costly to upgrade...)