rogerdv said:
complaining that it wouldnt work, that such method is not used anymore, that there are better methods (without providing such better way to do it)

I think it depends on detail. The higher it gets, the less feasible is it to swap body parts like Frankenstein. Imagine to use the same leg for thin guys, fat guys, and hot females. It can work fer very low detail / abstract gfx, but not for high detail / realistic gfx.

May that's what he thinks.

rogerdv said:
The project is an isometric RPG.

2D or 3D? Artstyle? Level of realism?

I would research what Bethesda RPGs do, for example. I guess they have certain character classes and model cloth once for each class. But they can still swap heads (or other details) within the same class.
That's probably a practical compromise, as few classes should be enough.

On a technical level, what you are proposing should work. I can think of other ways to achieve similar goals, but they wouldn't necessarily be better (or necessarily worse) ways. One alternate way would be to use morph targets to turn one mesh into a huge collection of different meshes, controlled by a set of independent variables. Or to use swap out the textures while keeping the mesh the same. Or to separate the body mesh (as a single mesh) from the equipment meshes.

On a project management level, it sounds like your artist does have other ideas, but is for some reason is unable or unwilling to talk about them. Maybe they need time to properly form and articulate their ideas before sharing them. Maybe they don't feel like their ideas are being taken seriously. Maybe you're being too confrontational. Maybe they already gave their idea and you already dismissed it. Whatever the case, try to resolve the problem by working with the artist, or remove the artist from the project if you are unable to find a solution. A team member who resents working on the project is a liability that needs to be dealt with.

rogerdv said:
It is 3d, and considering it is an isometric like, we aim for 10k polys per model, maybe hand painted style, but not too realistic in any case. We are a small team working on our free time (until we get funds), so our goal is to achieve a workflow that lets us work quickly.

I think your idea might work, but it still depends on variety of characters and artstyle.
Ideally your artists know about their technical options and required efforts. I agree with a light breeze. Sounds like a communication problem which needs to be resolved first.

But i never worked on games in a team, so that's just my two (at most) cents.