i see what ya saying
first, canyon isnt even near finished and i do try and give some back story as to why gdi have the ramps and nod have the tunnels in a few of the vids i made
walls ... refer you too this video
(red vs yellow)islands its the "lost" island there are tunnels and bunkers there just coz there needs to be
well i cant speak for islands and walls but canyon is still a WIP and is subject to change the the ramps are there coz theres a bloody big rock in the way (well thats my reason for them )