I am admittedly just drawing this up from what I have seen elsewhere but I felt the same - and it would certainly help get around the rotary better. But I feel like I have seen other threads say it's best to do this way, but for the life of me, I can't find them now or remember the reasoning/.
Yes, they do start looking a bit skinny. They are 24mm now, likely 7075. I am lacking the words to describe this but I was hoping the forces would mostly just try to move them along the X so not so much bending nor twisting as the bolts should hold them in place.
I am not sure if it's common practice to just kinda match the stiffness of the parts - so, maybe would make sense for those plates should match the gantry and frame walls?