Building A Setting Without Trying Too Hard

The main reason I chose to run 5th Edition for my most recent game is laziness. The depth and crunch of a 5e character is enough that by the time you've made 4 of them, you have a world emerging through the blank spaces of a character sheet and all you had to do is say yes.

I don't care what the elves should be like, I'm going to have fun no matter what because I'm playing Dungeons & Dragons and not doing my taxes. Do you know who does care what the elves are like? The person that thumbed through the book and saw a cool drawing of an elf and said "I wanna be THEM". They have a very clear idea of what the elves should be like and I guarantee you that if you let them decide they will not only be better at playing that elf but they will do work for you. They will populate cities and create nemesis' and fill your world with all sorts of great crap that you won't have to think about because THEY will know it, and they will feel like they exist in it.

Those of us that run games and spend our free time talking about and making games are smoking way harder stuff than those that just come around and throw dice a couple times a month. Don't let the fact that you spend your time reimagining the finer points of dwarves take away the joy of someone who just wants to do a Scottish accent and talk about binge drinking and beards. They had a long week and this is their day off.

When you think about what makes an enjoyable evening of gaming what comes to mind? Is it the specifics of what happened in the campaign? Or was it the fact that everyone was paying attention and cracking jokes and getting in character, and that for a few hours no one was looking at their phone or talking about how shitty everything outside their front door is. The stories people remember are not the most original but the best told. The games people remember fondly are the ones with good jokes and good snacks and no arguments about attacks of opportunity. 

Considering all of this the world building I did before I started this game was one sentence: 

"The wizards have been at war for over 500 years, and everything about it sucks."