Hi Scott, thank you.
For me there are many advantages. Aside from what you've mentioned having a separate net allows me to adjust my underquilt from inside the hammock. With an integrated net I'd most likely have to get out or at the least zip it all the way round both sides to do so. Depending on your hang height, you can sit upright with your feet near to the ground and still be inside.
Additionally, sometimes I will use the excess bugnet material hanging under me as a gear store.
Hope this helps, any further questions just ask.