The environmental benefit of a laptop with modular components is debatable at best and negligible at worst. At the scale of the Framework laptop's production it's meaningless.
As for the display, for a laptop supposedly intended to last years, every human interface component should be the best available option. The ergonomics are important for a long lived device. It shouldn't become problematic just because the owner aged. Otherwise the laptop ends up the same as any other where the owner tosses it after it becomes uncomfortable to use. All the benefits of modularity are lost if it ends up in a landfill.
As for the display, for a laptop supposedly intended to last years, every human interface component should be the best available option. The ergonomics are important for a long lived device. It shouldn't become problematic just because the owner aged. Otherwise the laptop ends up the same as any other where the owner tosses it after it becomes uncomfortable to use. All the benefits of modularity are lost if it ends up in a landfill.