Why games like Yoshi's Crafted World and Captain Toad are greenlit 'instead' of a WL5, I'll never know. I think it would even be up EPD Tokyo's alley.
Treasure Tracker is actually a good example of how Nintendo operates. They didn't decide to do a Toad treasure hunting game specifically instead of a Wario one. They started with the base concept of a puzzle platformer where the character can't jump and what franchise to add came later. Very early concept stages even had Link as the main character instead.
And honestly, with it being a EAD game, it was bound to be something Mario/Zelda/Animal Crossing/Pikmin or so on, because those are their series.
The big issue, as Glowsquid has touched on, is that nobody at Nintendo seems to be holding the torch to keep Wario Land active. They'll gladly acknowledge it, but it lacks key figures that keep it going, like WarioWare still has.
They could always outsource new Wario platformers, in fact, they did with World, Master of Disguise and Shake It and some Good-Feel Shake It interviews even teased the idea of them being interested to do a DS Wario Land, but I can see why it hasn't happened yet.
The lukewarm reception and sales of Master of Disguise, along with the back-to-back sales failures of Snapped, DIY and Game & Wario had to have done a lot of damage to the faith in Wario as a brand. Post G&W we saw the longest gap between Wario games and Wario himself didn't really get the push from Nintendo anymore that he used to get.
It feels Gold helped to turn this around and it was especially easy to feel this year, with Wario and Waluigi getting so much marketing push for Mario Golf Super Rush and Nintendo marketing Get It Together more than any Wario game in weeeell over a decade. The EAD/SPD1 merge may have also helped but I am nowhere in the know enough about that to say how true that is.
I do think Get It Together's success is gonna be a big help in getting Wario Land back, because it shows that Wario is still a brand well worth investing into.
