Believe me, I am well aware of Wario's situation. My most wanted newcomer after Ridley is Captain Syrup, and that's for a reason.
One song is more than none. You can't use an arithmetic that isn't true and then expect people to just nod and agree.
Additionally, and frankly, the Wario Land series in particular is pretty notorious for its really really weird music (Shake-It's soundtrack really is the exception to the rule here), and as much as I love the games themselves, I'm not entirely surprised that we're not getting a lot of music from them.
I'm pretty sure that there's a reason they axed the shoulder barge FSmash (which wasn't even really all that close to the actual shoulder barge, so I'm not even entirely convinced it was supposed to reference it).
While I love Wario Land and prefer it heavily to WarioWare, I can see why they're trying to emphasize the latter series a lot more; WarioWare is a unique game series, while Wario Land is based on platforming. WarioWare stands out and characterizes Wario more as a unique personality, while Wario Land is part of the greater Marioverse and has no proper unique characters beyond Syrup and some more one-shot type enemies such as the Golden Diva. And to my knowledge, the Ware titles do a lot better commercially than the Land titles.
Of course, this whole argument also leaves out the 2 standalone titles that tie into neither of the 2 main series - Wario World and Wario Master of Disguise. I guess that's better, though.