If you're just backpacking around and seldom need to look presentable, the crumpled look is fine. If you occasionally have to meet with someone at a nice place, however, or need to look presentable when you apply for that visa extension, wrinkle-free clothes can be a lifesaver.
I just flew all the way to South Africa from my home in Nashville--over a full day of flying before it was all said and done. I opened up my pack and pulled out a sportcoat, dress shirt, and slacks that looked almost as smooth as when I left. I can go to my meetings today looking quite composed. No iron, no fuss, no muss.
You can pick up wrinkle-free sportcoats and the like from a travel outfitter such as
Magellan's. Or you can just nose around the sale racks of your local department store and find something that works. The key is to get something with an ample amount of sythetic material, but not so much rayon that it's all shiny. With plenty of other clothes, including slacks, it's simple. Just look for "wrinkle free" or "wrinkle resistant." Then you can jam pack your bag and have no worries on arrival.