So yet again, I was thinking about the state of CP11, so I looked at the Final Characters for the Previous games
Brawl: Olimar (Pre-Release), Wolf (Post-Release)
Smash 4: Shulk (Pre-Release), Bowser Jr/Duck Hunt (Post-Release), Bayonetta (DLC)
Ultimate: Ken/Incineroar/Pirahana Plant (Base), Byleth (FP1)
So I do know the whole thing about putting the characters near the beginning/Middle to get the sales early, but looking at the circumstances around these characters, These characters couldn't actually be anything other than last
I'm not sure on Olimar and Shulk to be honest. They both have similarities in that they both come from New, though Niche Nintendo I.Ps. They aren't the biggest reveals, but they still are decent, especially since Shulk was somewhat of a popular request I hear. In any case, these characters probably could have been developed earlier, though they both are complex characters.
But when it comes to Wolf, He was one of, if not the Last character added to the game in terms of development, since he could be added with the time the team had left since he could re-use assets from Fox and Falco. And this also applies to Bowser Jr. Sakurai commented that Bowser Jr. was really lucky to get into the game, which implies he was one of the Last fighters to be added in.
For Duck Hunt, it seems that historically, the "Surprise characters" of Smash (which Duck hunt is classified as) typically are among the last characters to be developed. this applies to G&W in Melee as an example. And it also probably applies to Pirahana Plant, to the point where Plant had to be Pre-order DLC, instead of being a Base Roster
Incineroar and Byleth couldn't have been developed any earlier. A Gen 7 Pokemon was reserved a spot on the Base roster, but for awhile it was unsure who the actual Fighter would be. You can't develop a Fighter you don't even know who it's gonna be, and the Dev Team knows who the other Newcomers are gonna be.
This is also the same thing with Three Houses. While it was set that the Fighter would come from Three Houses since that was the game that met Nintendo's Quota of "a Fighter from a game people are playing now", Sakurai and the team couldn't start development without first playing a Early build of the game first. It's unknown when exactly Sakurai played the Build, but if it was not in 2018/Very early 2019, there's no way Byleth could have been in any other spot than the last character in Pass 1
This is also the Same thing with Corrin, since Fates was a really recent game (to the point the U.S didn't have the game when Corrin was revealed), however this might also be the case for Bayonetta, since she was the Ballot winner. Of course there is evidence that Bayonetta likely wasn't chosen strictly because of the ballot, as Data alluding to her came out 2 weeks after the Ballot was announced
But there is good evidence that she was the Last character to be Planned. There was one extra Placeholder spot that was added to Smash 4 internal slot count, and this ended up being used For Bayonetta. I also think they also waited after Bayonetta 2 was released to see the reception and everything. Unlike Corrin, Bayonetta wasn't chosen to represent a game people would be playing now, but because of her popularity.
The point of talking about all of this is to say that I don't necessarily think Nintendo chooses to end disappointing all the time. I do agree they do choose to reveal the bigger characters near the Beginning or Middle, but we have to establish why though
It's the type of characters picked that end up having to be revealed at the end or near the End. Characters like Corrin, Bayonetta, Incineraor, and Byleth couldn't be revealed any earlier if they wanted to, since it's likely by the time they had the assets/green light to start development, the other characters were well on their was to being developed
Now the rest of the characters theoretically could have been developed earlier on, and it does seem they were out-prioritized by more important characters in the roster in terms of development order. What I will say though is that the last characters tends to be among the more complicated of characters in terms of Development. Olimar, Shulk, Duck Hunt, and Bayonetta have Complex Mechanics going on, and Duck Hunt is special since he had to pretty much be brought back to life in 3D, since his last appearance was Duck Hunt on NES
The interesting thing is despite some of these characters being considered disappointing, Alot of the reasoning for the characters being added in was because of popularity with the fans. Wolf, Bowser Jr. (he might be more speculative), and Bayonetta were added because there were requests for these characters. Shulk is the definition of a character for the fans, since the fans are the reason Xenoblade got reprinted and stuff. Bayonetta is important here since she was the ender of Smash 4 DLC
People talk about how Nintendo doesn't care about the fans when Chossing DLC, especially when it comes to ending it, and stuff like that, but Bayonetta does actually go against that idea. She Actually represents an ideal type of Final Character that people want to see. The Idea of the FP2 ending on a character like Waluigi for example does have some creditability thanks to Bayonetta ending the Smash 4 DLC
So in regards to CP11, I think there is a good reason why they are last. If the character was not chosen to "Represent a game people would be playing Now", or isn't a recent character in general. then there is probably going to be some hooplah that makes CP11 a really interesting character. I trust Nintendo that they picked an ending character that will appeal to the people. This character was worth being developed, as FP2 could have just been 5 characters like FP1. Nintendo has a good reason to have chosen to have this character developed, and if it's not to be advertisement character, than DLC History in the past shows it's probably something the fans will like