There are some medical reasons why people need to use straws. In fact, that is apparently why the little disposable drinking tubes were made commercially: to halt the spread of germs in hospitals — the idea being that even a washed cup can be a little gross to share among sick people.
Straws made out of bark and grass had been in use before the turn of the last century, when they were made with paper. But in the 1960s, the plastic straw was invented and marketed to restaurants, and now here we are, with literally tons of trash generated by these items we don't even think about but that can be deadly to sea life. (If you want to become very upset, just look up “turtles plastic straws” on YouTube.)
The idea of doing away with plastic straws has been quietly percolating on the fringes of the environmental movement. Perhaps unsurprisingly, it's gained the most traction in seaside communities. Manhattan Beach, for instance, banned “polystyrene food service ware” in 2013. Some restaurants there even have incentive programs for customers who bring their own mugs and to-go containers.
One small step you can take as a consumer is to request straw-less drinks at bars and restaurants, and even in your delivery orders. (When you order food online, they only pay attention to the “special requests” section about one-third of the time, I've found, but it's a start.) If you really want to drink from a straw, there are metal versions available everywhere, including Amazon. They usually come with a pipe cleaner — isn't that thoughtful?
If you really want to be earth-friendly, you'll make an entire utensil set part of your everyday carry. We'll get there. Start with straws.