Games

We don't really have enough information about the setting to make that judgement in a direct sense. That said, basically every Pokemon story is one about defending the status quo, which is almost always portrayed as an uncomplicated good, so I don't think there's much of a basis for defending any of the villains except N, who was obviously right regardless of anything else said.

There's a really good video essay about the storyline for ruby sapphire, about the creator being inspired by the conflict between a local river delta ecosystem and a land reclamation project, I wish I remember who made it (I immediately thought cecilily but it doesn't appear to be her)

If we actually look at how non-dense the human habitats are in Hoenn and Pokemon in general, no. The actual design of the world undermines Magma's stated goals. If the world was different, maybe, I guess. You'd need some kind of commission between humans and land and water Pokemon to hash it out. But it's not really clear what Magma even intends to do with the land, if I recall.