I was initially totally stoked to discover that C-sites are destructible, but watching them in action, I'm afraid they're not quite fixed. Known issues in the new patch:
It only takes 1 construction material to make a healing tent, and I think 3 to make a catapault, etc. If this is intended, pardon me, but I always thought this would be more like a "many hands make light work" scenario with 25+ people donating a material. Or at the least, one guy throwing them down on each respawn, not just lolmagichereyougo!
Another thing is, if you drop a c-site and then use the materials, if you pick up somebody elses weapon it drops a new copy of c-site and materials, effectively giving you infinite of each so you can make ten siege towers in a matter of minutes, or cover your flag in healing tents. I think something similar to this is also going on with ladders.
If you catapault a wall down during round 1, it will be gone for all other rounds in that game. This would be great if you didn't have the chance to be autobalanced to defense after all your hard work only to have it bite you in the ass, haha.
Lastly, the potential to grief with c-sites is still very high, and I still see it being done. People covering the flag with a siege tower (which I might add is damn near unbreakable- at least a healing tent only takes 1 hit), and blocking areas with the now destructible, but still annoying, c-sites themselves. I wish we played in a community that would at least use these things for their intended purposes, and we have some people who do, who are wont to abuse them because they want to see them used properly, but others are, frankly, just trolls.