The HTC U11 has an IP67 water-ingress protection, which is the same as the iPhone 7. This means that the U11 phone can be submerged in fresh water up to 1 meter for a maximum of 30 minutes. It also has the high degree of dust protection ("Dust tight"). Having water-proof protection means that you don't need to worry if the phone accidentally dropped into the toilet or when you want to grab a shot while hiking on a mountain on a rainy day. It's great to see phone manufacturers providing a high degree of water protection for their high-end smartphones, and the HTC U11 is not exception. It's like if you release a flagship phone nowadays, you have to make sure it carries a high degree and certified water-resistant seal.
You might not appreciate this feature when you but the phone, but believe me, it's really great to have a phone with IP67 protection. Let me give you an example why I found it crucial. Regarding accidents, I wouldn't really spend extra on a waterproof smartphone just because it can protect the phone if I accidentally spilled water on it. I care more about having the option to talk with the phone and shoot with the camera when I am outdoors in a rainy day, which is usually isn't the ideal conditions for using your phone.
Most people will probably put their phone away in their pocket when it start raining. A few days ago I went to a hiking trip to northern part of Spain to the mountains. I really love taking pictures and lots of them, I am a very enthusiast photographer who always feel a need to take pictures of my latest experiences and adventures. That day was a rainy day. Unfortunately, I brought my iPhone 5S which doesn't have a water-resistant certification like the HTC U11. There were so many beautiful landscape and scenic views to shoot but I always had to take out my umbrella BTW, I was wearing a rain coat) in order to protect the phone before taking a shot. My friend had the iPhone 7, and he really didn't care about the rain at all. He just took the phone out and grab some amazing pictures.
Of course this is just one example from my own experience, but the thing is that in some countries and especially in the winter, you can really benefit from having a water-proof phone. I had many smartphones in my life, it only happened one time that water was spilled on my phone and it survived. I never thought about paying attention to the water-resistant of the phone, but once I start traveling to other countries, I found this feature to be really beneficial.
Whatever your reasons are, I think many people can benefit from having an IP67 water protection and enjoy it on their new HTC U11.. hey, you can even shoot with it underwater I think, but I personally wouldn't do that, don't want to test the phone's water-resistant to its limits.