Funny enough, I was just reading up on that the other day. The name 30-30 refers to .30 caliber propelled by roughly .30 grains of what was, at the time, a brand-new technology called "smokeless powder."
I was thinking it was more along the lines of a date or whatnot, which is why that info stuck.
As to the question of why I think the Gov't would "let us" have black powder, it's not about letting, it's about the fact that we pretty much have the ability to make it at home from (fairly) common ingredients. Smokeless, not so much.
In regards to why the D's would "let" us have percussion caps, it's kind of the same thing. Percussion caps can be made from some fairly common items as well and it wouldn't take much to modify on-hand brass to accept them in the place of modern smokeless primers.
As Doctor_M said, it's never a bad idea to have a plan B, C, D..... etc.
I'm actually really tempted to get a Rem Model 8 and try some BP and cast lead loads to see how it goes now.
Ahh, cause lawmakers make laws that make sense LOL
they will simply do the opposite of what we want to the extent that they think they can and say "its for the children"