I am not sure whether Japan factor is really that important. I don't buy Banjo being so popular in Japan. I guess 400k sales is respectable for Japan market... But I don't think that's huge different from... like Halo 3's 110k sales. I seriously doubt Nintendo would consider "290k" as world of difference.
And Crash sold better than Banjo there. It's not like 5 million Japanese Smash install base would be familiar with Banjo. We had Japanese kids calling Terry "buffed Pokemon Trainer."
I mean, for what it's worth, Banjo was clearly a special case no matter how you slice it. I'm not saying he's an "exception" or anything, I do believe the gates are open to western characters if they so choose to continue in that direction, but I highly doubt Nintendo was studying the sales data from a game that released two decades ago to justify whether or not Banjo could be sold to a worldwide audience. At this point, anyone who was following Smash likely knew who Banjo was whether they played it back then or not. He's a legacy pick, for all intents and purposes.
In that regard, I don't think this matters all that much for Crash in and of itself either. But Crash being such a new request may put his sales figures under more direct scrutiny, while Banjo is a legacy pick and gets by more on sheer name recognition. Conversations about Banjo in Smash never really died down, while Crash fell off the map for a little while in general and never really had a role in Smash discussion, so it may be worth considering whether or not his revival reinvigorated what was once a pretty strong presence over there. Granted, in all fairness, I do recall Crash showing up on some Japanese fan polls I've browsed through so perhaps his initial legacy has had a lasting impact after all. It's really hard to discuss these things outside of our realm of direct understanding, I think it's a valid concern though.
I'm never that comfortable using Banjo as a direct comparison for any other characters because like... B&K are really the ONLY ones who have been requested for so long with such a special connection to Nintendo's history. There is a very clear additional incentive to adding Banjo, just as Minecraft is the biggest game in the world which further justifies Steve. I guess what I'm trying to say is that one door opens and paves the way for more, but while many see this in and of itself to justify that it
can happen again, these discussions often leave me wishing more people told me why it
will.