[Lindril Arvilya]

Like many others here, The Silmarillion increased my appreciation of LotR. I think that the qualities and things valued by the 3rd-Agers are more important than those valued by the 1st-Agers. (I've worded that wrong, but it was the best I could come up with.)
In the First Age, what were the wars fought for? A set of jewels. The so-called "good guys" were greedy and hasty. (Some of them, anyway.) They made the mistake of taking their obsession with the Silmarils too far and swore an oath against basically the rest of the world.
Now, for the 3rd Age, I'll break it down to the fact that the so-called "bad guys" are trying to take on the rest of the world to get what's theirs. The good guys aren't fighting to keep this precious ring. They're fighting for peace, harmony, pans, pipweed, and a good ale in The Green Dragon.
For me, The Silmarillion brought home the humanity of LotR. The real heroes in our world aren't necessarily those who fight grand battles, swear oaths and so on... they don't want to fight in the first place, and being forced to, they just want to protect the simple things in life, the ability to go home to a good supper, to pet the dog, to drink their coffee in peace.
It's interesting and fascinating to read about these grand battles, oaths, and treacheries, but in the end we all like to go home, pet the dog, and read our newspaper.