I suppose I expect to see not just how people lived in the past, but also to see the effect that time has had on what they made. I like looking at a fragment of a wall and contemplate the amount of time that separates me from the folks who put it up. Knowledge that the wall was built in my lifetime just completely ruins it for me (no pun intended).
That said, I did see some great recreations and I learnt much more about the past from them than I had from ruins. Some folks do impressive amount of research about what life used to be like and recreations are probably the best way for them to share what they learnt.