Honestly like, not even down to sales numbers, I think the biggest reason that I would assume the DK series might only be repped by Donkey and Diddy alone is simply 'cause the rest of the DK series isn't a creation of Nintendo of Japan. Not counting Mario Kart Wii (that game had everyone) Donkey and Diddy are the only Kongs to appear in pretty much anything made by Japanese developers, so I feel there's a pretty clear bias there. It's the same reason why the Prime series is mostly looked over for content for Metroid, and why you're probably not gonna see Mike Jones from StarTropics in the game. There's no pride for American-made stuff for a Japanese developer.
However if we do go into sales numbers (which really aren't end all be all indicators of series popularity, but that's a different post), there's something there too. As well as the Retro Studios DK games may have sold here in the US, it doesn't really change the fact that DK's not popular in Japan at all, especially compared to Fire Emblem. Awakening sold 245,402 copies in its first week, which is more than the first week sales of DKC: Returns and Tropical Freeze COMBINED (169,260 + 38,265). And 3D World (101,798) massively outsold Tropical Freeze in Japan.
And as much as Little Mac can be seen as them appealing more to the US audience I really don't think it should be seen as anything more than an exception to the rule, that rule being that the development team is still gonna look homeward for insight on series popularity.
EDIT: I mean, don't get me wrong, I'd love for Dixie Kong to be added that would be great (though I doubt I'd play her much just based on the fact I've never really liked how the DK series characters played...), I just massively disagree with the idea of thinking that DK and FE are equal in the development team's eyes. I'm just saying I'm not getting any hopes up about it.
However if we do go into sales numbers (which really aren't end all be all indicators of series popularity, but that's a different post), there's something there too. As well as the Retro Studios DK games may have sold here in the US, it doesn't really change the fact that DK's not popular in Japan at all, especially compared to Fire Emblem. Awakening sold 245,402 copies in its first week, which is more than the first week sales of DKC: Returns and Tropical Freeze COMBINED (169,260 + 38,265). And 3D World (101,798) massively outsold Tropical Freeze in Japan.
And as much as Little Mac can be seen as them appealing more to the US audience I really don't think it should be seen as anything more than an exception to the rule, that rule being that the development team is still gonna look homeward for insight on series popularity.
EDIT: I mean, don't get me wrong, I'd love for Dixie Kong to be added that would be great (though I doubt I'd play her much just based on the fact I've never really liked how the DK series characters played...), I just massively disagree with the idea of thinking that DK and FE are equal in the development team's eyes. I'm just saying I'm not getting any hopes up about it.