Certainly never does any harm to have a paper print out of any important stuff (presentations, tickets, etc.) with you on a business trip (I say no harm, it doesn't help the environment,.
Can we stop the myth that paper destroys the environment? The paper industry does not destroy trees, they are not cutting the resources they have access to and destroying their own future. They plant tons of trees to ensure they resupply their stocks. It's a renewable resource, and on top of that a LOT of the paper you buy is recycled.