I don't think you're seeing the bigger picture... or maybe you've never been a lone wolf. We generally do not raid, and instead stay hidden to survive. If you really wanted to raid, you'd either join a clan or group of bandits. What you're saying does not make any sense. What exactly is not a good idea? By making C4 uncraftable and rare to obtain, you are providing newbies and lone wolves an opportunity to build their structures, without immediately getting it destroyed by large groups who have an ample supply of C4. Let's say we made C4 easily accessible to everyone. In the rare case that a newbie or lone wolf is able to retrieve some C4, how much C4 do you think the "clans and other large groups" would have collected by then? Basically, there would be no point in building anything, with all the C4 exploding everywhere.
With that said, you mentioned Grenades. That is one thing I can agree on.
Also seeing this post now extremely just made me facepalm... you say "we" as in you speak for most lone wolfs.. You don't I know 50+ lone wolfs that enjoy raiding on a daily basis.. not all of us are sissies who like to stay back and hide.. we know howto aim.. we have guns.. and we know howto use them..
EDIT: Grenades as is do actually serve a purpose 10-15 of them well blow up a door (gotta be carefull with aim)