It's not really a choice between comfort and trend, but more about your lifestyle. If you spend a lot of time on walks, traveling, or just don't like holding your phone in your hands - yeah, a strap really helps, your hands are free and the device is always within reach. But if you're at work or home all day, it's just an extra accessory you quickly get used to and forget about. As for safety - no issues if you pick the right attachment so the phone doesn't press on your neck or mess with your circulation, and the strap itself is made from decent material without sharp edges.