Nah, I think you’re on point with pretty much all of this. If they add Master Chief or Marcus Fenix for example, some might enjoy them. I personally would loathe the idea - they’re both poorly written, stock one-dimensional characters in their respective franchises, with no potential for varied or unique movesets that would fit in KI. Literally the only reason would be to attract more “casual” fans to KI. But entire franchises have been ruined by going down the “casual money” rabbit hole, at the expense of the core fanbase. Why should KI go down this route, when it’s been shown that these casual fans typically don’t stick around long-term, and when KI at this point has just started to build a real solid identity of its own?
And like you say it can go both ways - Joanna Dark is one of the only characters being floated around right now that I think would be a decent fit for KI, but others might hate the idea just as much as I hate the idea of someone from Halo or Gears. No matter which guests are added, you’re going to alienate some of your core fanbase, it’s unavoidable. Some might say “Well, you don’t have to buy the characters”. Well, yeah, but we’ll still have to fight them online, and see others play them on stream. They’ll still be a definitive part of our KI experience.
Also, traditionally guest characters in FGs have been horribly broken and overpowered on release (looking at Netherrealm here primarily), or garbage tier like Link in Soul Calibur II. There’s a fine balance that doesn’t seem to be struck too often, which seems to me to show that the developers do it primarily for financial purposes and not because they have an interesting vision for these characters.
And speaking of Soul Calibur, the one series that is probably most known for having guests; Link/Spawn/Heihachi, Yoda and Darth Vader, Ezio from Assassin’s Creed. Did these characters go over well with the core fans? Did they help Soul Calibur maintain a solid fanbase? I’m not a massive SC fan by any means but even I can tell you that the series isn’t exactly a picture of health. Not that having guests is the main cause of that, not at all, but in terms of retaining casual fans alongside its core base (which like I’ve said is typically the main reason to include guests) that series has failed, and failed hard.
So for me the question becomes, do IG and MS have solid gameplay ideas for these guests that we now know they’re adding to KI? Are they adding characters primarily based on whether or not they have designs that will fit the KI universe and will add new and inventive playstyles to the already wildly varied cast? Or are they just adding Rare/MS characters simply because they can, or because they’re chasing after casual $$$?
If it’s the former, then I’m still totally unconvinced that guest characters are the way to go but I’d have faith that IG would at least have the ability to do something fresh and exciting with them. If it’s the latter then I’ll be thoroughly disappointed, and like others have said, I feel it would really put something of a downer on what is one of my favourite franchises. I’ve mentioned it in other threads, but if this game becomes some form of “Xbox All-Stars” crossover franchise (that’s extreme hyperbole at this point, but it’s certainly a possibility) then they’ll have lost me as a player and a fan.
But I certainly hope that doesn’t happen. It’d be a shame for KI to have come so far out of 90s obscurity to create its own identity among today’s modern fighting games, just to devolve into a mashup of characters that have nothing in common with the series. Personally I’d be very interested to read some of IG’s thoughts on the matter.