I. Have. No. Clue.
It's like an entire team or department within Nintendo (and Bandai-Namco, they helped develop MKT) didn't get the memo that Nintendo had requested CyGames to rein in the microtransactions.
Simple lack of communications most likely, and severe overestimation of how much people are willing to pay in one go (and without alternative pay amounts).
Thing is, the $40 Diddy Pack was memetic for all the wrong reasons - the Cheaper than Diddy twitter account was created as a reaction to this. And it's a main reason why MKT underperformed severely. Dungeon Keeper iOS and Mega Man X iOS are two other infamous examples of heavy-handed monetization gone wrong.Why do people allow this to continue?
Microtransactions, especially mobile ones, are a contentious topic. The article I quoted notes that "Only 4% of Candy Crush players, for example, spend on the game. And 10% of this 4% (or 0.4% of users) generate 50% of revenue." The 0.4 % are commonly referred to as "whales" and are the portion that a lot of mobile games aim towards.
Candy Crush, IIRC, doesn't do just $40 packs. Much smaller increments (like $1 / $5 packs) + larger but more expensive bundles are common. It's intentional, but not always meant to "gate" and frustrate players until they spend (although that's common too). Paying is also a shortcut or a way for a player to get the best characters, cards or just the best-looking costumes. Then there's the lootbox issue, which adds to the shenaningas but is another issue entirely.
From an Average Joe / Jane perspective, spending $5 on a mobile game is pocket change. Even if (s)he winds up repeating it.
From the developer's perspective, the mobile industry is incredibly cutthroat. Again, there are like 1 million+ F2P games just waiting for the F2P money if Say Game X doesn't go F2P (which is what happened to Super Mario Run). Which is a main reason why so many mobile games are F2P and use this model.
As for what to expect for the Partner's Showcase... MH feels a little given, but I can't be 100 % sure on that. We're likely to see some low-profile games, but I don't think one game will be as badly recieved as WWE Battlegrounds. And yes, I have my hat and salt on standby if I'm indeed wrong. At least one multiplayer focused port (a la Rogue Company / World of Tanks) feels rather likely IMHO.