I've played several games of Seven Wonders now, and I'm still figuring out a lot of the strategy. I've learned that every card has its place and advantages, but the one group of cards that seems most useless is the blue cards in age 1.
It's not that the blue cards in Age 1 are bad, it's just that the other alternatives seem better. If you can take almost any brown, gray, or yellow card instead it seems like it's almost always a good idea to do so because the will help you get more points for every single turn in the future instead of just being worth 2 or 3 at the end of the game. If I can take a green card instead of a blue I'll usually do it unless I'm really short on money and have to pay my last coins for it. I'll also usually prefer red over blue in the first round because they usually give you close to the same point value at the end of the round as well as help you win future wars.
If you don't need the extra 3 coins from discarding or are planning on using them to get some Age 2 blue cards I can see them being valuable. But won't you usually be able to use the money to get something much better? And isn't it usually a better idea to focus on getting resources so you won't need to use the free-construction benefit? When is it a good idea to pick the Civilian Structures in the first Age?