It was another East v West thing. Richter is more well known and requested in Japan
He's much more popular than Simon is in Japan.
How about Ressha instead? It means Express.
I mean Richter has one of the most iconic line in the franchise that anyone would recognize
Part of Simon's moveset is literally ripped out of Richter since Simon never used some of these moves. Sakurai even says during the August direct that you can't tell who is the echo fighter of who since both were used to make the moveset. That's why Richter is in, Sakurai looked at both of these characters when deciding the Castlevania character. And it's not like Simon and Richter were in the same game, both were the protagonists of different Castlevania games from different eras.
Hmm, OK, those are good points.
But still, was he really that deserving of a spot over character like Shadow or Dixie? Like Sonic as been in the Smash franchise for 3 games now, yet he still only as 1 character, while Castlevania get a free echo first time. You could say it's to make all fans of Castlevania happy and to make sense as to why Simon use Richter moves and vice-versa, But Donkey Kong and especially Sonic are much well-know franchise those days than Castlevania, so if we use the "deserve" argument here, I feel like I would have put priority over Shadow/Dixie than Richter. (Also Sakurai could have totally pull a Ness with Simon and say he asked help from his descendent or some **** during to the event of Judgement to learn their moves to explain how Simon could user Richter moves, it might have sounded bad, but Sakurai could have use that card without too much problems imo)
As for Kasumi place, well, I guess it depend as to how you reacted to Corrin inclusion and if getting angry at a echo fighter, which don't take alot of works anyway, is really worth it or not. In all cases, I wait until we get more info on her before I say something I might regret.