When I look at DOA6 as a "complete" package and also remember the things that happened to the game after its release, there were a good couple of decisions from (mostly) KT that make me shake my head to this day, if only they would've let TN to do their thing for 95% of the game's life cycle, then we'd probably look at a completely different and most probably better product than what we have now.
Honestly, think one part of the reason is just the game genre itself that enforces KT to go with that tactic because it is business at the end of the day unfortunately. Fighting games costs money and are very niche, added that DOA (the fighting game) is not only one of the higher niche ones, but also has a lower populated community than that of DOAVV/X now.
KT: It's an action game. Always growing and people are buying it every single day. Over 40,000+ active players so eh no point.
"Why charge hair color on DOA (Fighting Game)"
KT: Game's not growing. Didn't put in the budget because it'll be either the same number of people buying the game, or the same amount of active players which is less than 200, so cash grab it is.
I don't know, I just think the higher ups in KT saw DOA players as easy to take advantage of so they tried to push monetization as far as they could. DOA6 looked like it was being lead by cold business decisions even more than DOA5 was.
It's not just that it's a free thing in Nioh 2, any of their competition (other FGs) that let you change hair colour had it for free for years. Of course it was gonna look bad.
Doesn't even matter if you don't care about cosmetic things and never intended on buying DLC other than characters, it was enough to just plain be a really bad look for the publisher. Plus, when a publisher is focused on doing things like this, its no surprise if they're dropping the ball when it comes to gameplay and other content.
It's more towards their recent perspective of how they treat the Fighting Game genre, because otherwise they wouldn't have done it in the first place, I don't think they are Mihoyo levels of greed yet. It's likely just their marketing team.
I definitely agree that they may have been taking advantage of the general base, but they've been doing that way before the hair inclusions.