Malladus looked specifically like a train with a Ganondorf face on it. I'll admit I don't include "sequel" bosses such as Majora, as they were intended as "other adventures" beyond Ganondorf. And while Vaati had two games to himself, he appeared alongside Ganon in Four Swords Adventures.
Or maybe it was a Japanese Demon answer to said villain? A creation myth of sorts? I don't consider that insulting. I consider it a reference to Shinto, which added to the mythological quality of that particular leg of the series, not to mention the overall mood of the game. Zelda spent most of the game as a Miko of sorts, so this made sense.
Sometimes evil doesn't need a reason. It certainly didn't need a reason in Ocarina of Time, and in many other situations, he is simply the "big evil" to introduce the smaller "villain of the day". Skyward Sword was no different there. The only game in which Ganondorf had a motive that wasn't out of a Saturday morning cartoon was Wind Waker, and that game was pretty much spit on by "real fans" for years. I was sure as heck around to see it, as the first Zelda game came out when I was 6.
So let's just drop the whole who gets to be a real fan thing, okay? Someone saying that they don't feel it was inconsistent with the other games may have their reasons, as I do.
The Demon Train isn't Malladus himself. Its actually a living train used by Malladus and Cole to get out of the Dark realm. Malladus looks like a disembodied blue skull himself with no resemblance to Ganondorf.
Its the lack of screen time for Demise and nonexistent character developent I take issue with rather than a Demon existing as the explanation for Ganondorf. Had he been a major character in SS that would have been fine but he just transformed from a pinecone we had been fighting the whole game, challenged link to a duel straight away and then died.
Perhaps I'll make a proper thread for the inconsistencies of SS soon with the evidence plain for all to see.