That's not entirely true. Because, at first, most maps were pretty much open. Then Mustikki (who was at that time map manager) and others started "fixing" them by adding invisible walls to places which were considered as exploitable. Just because some places haven't been fixed by invisible wall, doesn't mean it is okay to abuse it.
Don't get me wrong, I'm not in favor of limiting the gameplay and I'm especially against invisible walls. Those places OP posted are all relatively easily reachable and most of the people know how to reach them and which tools to use. But devs themselves have stated their view on this by putting invisible walls on maps and not allowing access normally to most roofs. Sometimes their intention to "fix" things reaches pretty extreme levels, for example, there is a map where it is impossible to come near certain building because there is a porch nearby. Some braniac has put invisible wall all around that specific area (around the porch), had a laugh when I spotted it 
This discussion should be moved to General Discussion sub.
to me if devs removed ladders its for stop giving spots who give huge advantage.
and the spot im showing in screens are just missing invisible walls.
and last time i made similar thread it finished in flooding section ... so i took my chance on this one.
i just want a simple yes or no from an admin. just to know if i can poll kick one of those roof camper or not when there is no admin on server.
Honestly, no it would not be a glitch.
It is merely a place that the developers did not have in mind when creating the map.
It'd be a glitch if you had to use some exploits, like jumping against a wall which magically bounces you back if you hit the right spot over some other wall to get underneath the map or out of bounds or whatever.
Here some examples of exploiting glitches on CoD4
about it's glitch or not i just dont find the proper word but to me it's not legit acces if you prefer
