Hint: To export characters you need to import and bind the games actual IK skeleton and bone grouping/naming/structure/tree, in GR2 SDK this is very very easy, it's actually the only reason anyone ever uses GR2 far as I know) without that SDK plugin it's a manual job, that means 8+ hours per (new) character mesh you wanna convert to D:OS 2, new weapons and especially hair meshes are a nightmare within nightmares. Since those bind to specific bones, arm skeleton was imported with them (it's done automatically in the GR2 SDK I think) this however means if you change the skeleton you literally have to remake all the weapons yourself..... and since you don't have the GR2 SDK within MAX you can not easily do it automatically
Anyhow... just having a GR2 exporter is entirely useless for character additions, new enemies, weapons, body and hair styles etc. Anything where you need to adhere to IK and bone regulations you are gonna suffer hard from GR2 inflicted issues.
I guess that when you say "new weapons" you mean new TYPES of weapons, that require new animations, like a pair of nunchakus or a pistol. But creating a new sword, or a new axe shouldn't be that troubling as long as you respect the proportions and size because animation will be absolutely the same.
At least in D:OS 1 it really was "ALL" meshes in any way related to characters, weapons, hairs, heads, bodies, armors* that you absolutely needed the importer/converter for to even do anything *to* (and armors had the extra quirk that their textures replaced part of the body texture, because of how the bodies were colored (by shader..) this is not a bad thing, but Larian due to how they coded that destroyed ANY possibility to import *more* realistic or prettier body skins or faces.
The only meshes that didn't require this voodoo, were scene stuff for the map editor, in that case you could export from Max and assorted just fine convert to GR2 and have something more or less working... until you tried to create a collision mesh that the map maker could actually use to create proper collisions with... then it got complicated, and again, with absolutely ZERO info from Larian how to do that it was painful to create the workflow for this. And due to flipped color channels (on normal maps of all things...) you also had tons of extra fun after clicking "export" as you never could know whether your exported mesh had a working collision (for the map-maker) or not until you tried it...
If you peruse the topic in the D:OS 1 forums about art stuff and converter/exporter/importer you can see what a pain EVERYTHING was thanks to GR2 file format and the idiosyncrasies that you suffered wherever you went because of it. I doubt this will change in D:OS 2... Larian uses Granny and, thus far, refused to give us source files with the RIG intact and thus, GR2 files remain an obstacle with no way around it.
Worth noting that the only reason armor meshes for Skyrim exploded was that someone created an export ready "template" scene that was part of a tutorial that ended with that mesh in the game. It was involved, but it worked if you followed it. I don't wanna be all negative but unless Larian takes modding seriously this will be a repeat of D:OS 1, at least for the 3D pipeline.
Namely for modders, there isn't one (a defined 3d pipeline)
Ps.: I meant that modding D:OS is *neither* easy nor fast vs creating art in Unity and linking it to controllers and what not where that is super easy, and instant (drag and drop, literally) . Made quite a logical fault in that paragraph
Obviously making a full game in Unity isn't easy nor fast, but it's a lot easier and faster than modding D:OS 1....
And believe me, I want you to make big fantastic mods with new scenery, weapons and characters and enemies in D:OS 2 which is why I want Larian to notice that we need more than just an exporter... we need the source files for the RIG and example templates for each element (Body/HEAD/Weapon/HAIR/ENEMY/ANIMATION........) and then we could work with just an exporter fine*. But exporter to GR2 without any templates, would not get you any closer to bringing your imagined campaign to life.
The pipeline, as OP said, is undefined and opaque. Same as it was for D:OS 1. And if this remains this way up to release, then modding will not get the boost that I most definitely want it to have. More mods for D:OS 2 means my backer money finds dividends many times over, and not just in D:OS 2 as a self contained experience. ^^
PPs.: And yes, I absolutely agree, if modding becomes too difficult then that scares away all initial interest and hype. We still get some mods (maybe) but it would be a a great time consuming effort by skilled individuals that grind through all the barriers. And the more difficult it is, the higher the risk that modders lose interest. (Can't blame them for this either, people have lives and jobs and families to care for)
So yes, modding needs to be simple, but also the 3d pipeline needs to be defined properly. It needs to be part of the actual editor for D:OS 2 actually, and as long as Larian uses Granny I don't see how they could do this without getting into trouble with Granny
