This feature request had come up in the past. I have taken a look at it. However, the tricky part is how to make the connection from the group to the asset node, and still have it “work nicely” for the user.
Maya relies on attribute connections for DG evaluation. So ideally, when the user chooses a group for input, the plugin would connect all the children mesh nodes to the asset.
But after the initial connections, what happens when a new node is parented under the group? A new connection needs to be made. Ideally, this should happens “automatically”. Otherwise, the user would have to disconnect the input group, and connect it again. Though, other built-in Maya tools that can use groups as an input probably have the same limitation. So thinking about it now, maybe this scenario is rare enough that we can just live with it…
But after the group is inputted, there are still (at least) two things that need to be considered.
1. Since the group has multiple mesh nodes, the user is likely to expect that multiple mesh nodes to be outputted. This is currently not easy to do, because in the Houdini side, the polygons are all bundled together as one “geometry” (e.g. one SOP or one connection). So when outputting this geometry back into Maya, there needs to be a good way of separating the geometry back into multiple pieces. The “Houdini way” would be to make use of the “name” attribute to identify the pieces. So this is doable.
2. The original transform hierarchy is lost. All the meshes that are inputted have the world transforms baked in. And the user probably wants this to be maintained somehow. This would affect both inputting and outputting sides.
Anyway, I'll end my rant.