The way I have looked at it (and the way my players have looked at it) is we are playing dungeons and dragons and they are adventurers. This isn't blacksmiths and horseshoes and the game is about adventuring, not building and crafting.
The backgrounds do add some flavor and maybe if you are in a keep during a seige the guy with woodcarver tools can pitch in to make arrows, while the guy with smiths tools can help repair armor and the guy with carpenters tools can work on the catapults. Other than that though they aren't making stuff on down time because that is not the game we play. When one adventure is over the story is moving on.
Heck my players have enough trouble finding time to make it to the shop and buy some studded leather or a chain shirt to upgrade from the original leather armor the were born with.
