It just popped up for me. Is there any reason currently to hold out and not open it?

The only reason I know of not to crack it open is that it lets you see your vault % without having to dig through the game files (i.e when you hover over the icon it'll say 103.4% vault progress) so you'll know how close you are to the next time you can crack it.

Not really that important if you care about the wildcards

No benefit I can think of.

Thanks.