Correct, but the thing is the series were not ignored if you look beyond characters. Remember characters are only a small fraction of what constitutes "representation".
Of course, but characters really is the most important part. Significant series really do deserve characters if at all possible. Nobody would accept it if the Legend of Zelda had no playable characters, but instead had 5 stages, 43 trophies, and 62 stickers on the basis that constituted representation. I would argue that Custom Robo, Starfy, Sin & Punishment and Golden Sun all meet the bar for "significance". If they do not make it in; it will be because Sakurai is not willing to move away from the Nintendo first parties and subsidiaries when considering which series get characters, not because the series are inherently unworthy of characters.
Considering Punch Out, Murasame Castle, and Mii will likely be included, it does not leave a lot of room for other series. I'd even go so far as to throw Xenoblade into that group, but I'm not going to deal with that discussion right now.
Murasame Castle will be the retro entry like Pit and Ice Climbers, rather than being entered on account of the series itself - you notice I excluded retro characters from my list earlier. I have also argued for the inclusion of Punch Out!!'s Little Mac and Mii, I'm not hypocritical on those grounds.
It isn't about series. You are coming at the situation as though there are only two possible scenarios, completely forgetting about all of the other variables that factor into Sakurai's selections. In fact, the only time Sakurai has even come close to discussing series representation was in reference to Mario and Pokémon because they have so many characters to select from.
He's not discussed series representation because, prior to this point, it was not really an issue. Now? As Holder of the Heel mentioned above, we've reached the point where all the really obvious boxes are ticked, and now we need to decide: do we include minor character X from a series that is already present, or do we have main character Y from a series which is not present. At this point, it becomes increasingly more obvious it is about series.
As for Falco, I will give you King DDD, but not Ridley. Reason being that Ridley is more of a Western obsession and has never really had the same following people seem to attribute to him. Not to say there aren't those in Japan who want him, but at the time when there were more characters to choose from, he didn't excel. In fact, according to the official Melee poll results, Metroid had six votes where as Ridley did not even make the list. Much hasn't really changed; the Metroid series has historically never really been as big of a deal in Japan as elsewhere in the world.
Long story short, it is easy to understand how Falco got in over Ridley when he (Falco) has seven votes to top all characters for the Star Fox series, while Ridley likely had one or no votes.
Are you really trying to argue that Ridley is less important to Nintendo's history than Falco? I mean, I understand there is always a degree of subjectivity to these arguments, but: Ridley has been present since the NES, and predates Falco significantly. Ridley has been an opponent of Samus in every single Metroid game bar 2, Hunters and Prime 2, and is the most frequent Metroid antagonist, and Metroid itself is more important than Star Fox, given it was the genesis of the Metroidvania genre, making Ridley the obvious second choice.
The official Melee poll was taken from a unweighted sample of 710 voters. Do you realise the margin of error on even a normally distributed weighted sample of 710 voters from a population of 4.9 million (the total amount of people who bought SSB in Japan)? It's about +/- 3.7% which is 26 votes. That means any two characters within 52 votes of each other could actually be equally popular. Nintendo knows that, Sakurai knows that. The real purpose of that poll was nothing more than whipping up hype - to think they were actually paying attention to the results is farcical. They're not morons, they know how statistics work. In addition, the poll was conducted before the release of Metroid Fusion, every single Metroid Prime game, and Other M. When that Melee poll was conducted, there had not been a Metroid game since Super Metroid. As I said, there is some degree of subjectivity, but arguing Falco is more important than Ridley is stretching subjectivity to the absolute breaking point.
But as Golden said, if you imagine for a moment that neither Falco nor Ridley had been in Brawl or Melee, and sat down and said "which one should I introduce for SSB4", it would be Ridley.
