I know it sounds strange, and it's totally nothing more than a guess based on the limited vantage I have as a fan, but it seems to me, like the DLC budget was not quite the "bottomless pit" people treat it as, where any character would be on the table.
I only say this because, reading volbound's post, I do agree that the characters we got aren't the "top of the charts" (unlike him, I don't have a problem with that), and it strikes me that of the five, characters such as
and
probably weren't nearly as costly to license as most of the past third-parties. Even if Ryu Hayabusa was intended for this pack, I'd group him with those three, rather than
, who, based on series stature and company, I would guess, was an exception, and more in line with past inclusions, price-wise. And obviously Byleth is first-party.
Of course some of the budget was also relegated to the trailers, which the DLC last time didn't really have to the same production level, but on the whole, it really wouldn't surprise me if some of what dictated these choices over others was the price tag.
It'll be interesting, going forward, if the trend of primarily b and c-tier third-party IP continues over the remaining a-tiers.