It doesn't really add much game play other than the gathering part. Once you have them you simply just place them on the door/wall.
Yes I have made C4 by myself, yes it takes time, and this is not a discussion of how hard C4 or something else with the same function would be to make/craft.
It's about what other things that could be added/replace C4 to change the way how doors are taken down. Right now, as you said yourself you just simply click two times and door goes bye bye.
Well yeah obviously? But that's because you've wasted hours before you simply click twice on a button..
Like what would you expect to happen?
It's not that you farm for 10 minuts and you got 5 C4 and simply click twice and you got fat loot..