No problem but I think we see things from a much different angle.
I don't know the exact answer, you should ask a "global moderator".
But, I think, it basically comes down to how much time the developers can or want to spend and what they think what should be added or not.
And when something isn't there, some people become developers themselves.
Perhaps you can contribute to the open source community too.
I think you can just add gameandwatch in line 50 of /home/pi/RetroPie-Setup/scriptmodules/libretrocores/lr-mess.sh
I haven't tested though !
Let me know if it works for you, perhaps we can learn from this.