The bricks generated by the modifier all have clean geometry. This means it's not just some cubes and cylinders put together, and therefore the bevel modifier is perfectly appliable on it. The mesh contains a lot of n-gons, this desicion was made to keep the vertex count low. But it's not gonna cause any rendering issues, since the generated surfaces are flat.

Absolutely, this modifier is only in its early stages, not just new brick types, but other upgrades are also expected.