I don't really like this idea.
Cubecraft's cage system is too plain and simple. Also these requirements aren't really the most suited for what you get. Imo.
These designs also don't get my wow factor up. There are many blocks combinations/palettes that could do many times better for cages.
Not to mention that players could simply build up to mine the resources from that specific cage in games such a Skywars.
Anyway that's easily preventable. So I wouldn't worry about it too much.
But.
These cages could be implemented as a filler update. So people won't entirely lose their hope in Cubecraft's cage system. Meaning that the Cage system could be improved! Into something never seen before. I'll post a thread about it someday. Soon™
wow this was the best suggestion thread I've ever seen xD (not sarcastic).
*cough* vvvv