This is one of the most important buildings on earth

Because seeds from almost every plant are stored there for safe keeping.
https://en.m.wikipedia.org/wiki/Svalbard_Global_Seed_Vault

neat

It can withstand the power of a 5 megaton nuke, it's that deep in granite.

That is like asking why would anyone want to kill someone else for diffrent beliefe....
And there is ISIS already, so deal with it, there are surly some people who would like to destory even this.

I know this is a really late reply but all of the seeds stored there are considered back-ups of seeds that are stored elsewhere.

I learned about this place and others like it through a James Rollins Sigma Force book.