Actually, the notch was deliberate and required a lot more engineering effort... they had to make sure the display worked in that irregular shape and had to rework the UI as well.
I honestly don't get the notch hate. It can easily be hidden via software with a faux bezel. Apple could have been lazy about it and added physical bezels like every other unimaginative Android vendor but they decided to go the extra mile to create something cool, new and distinctive which they've accomplished with the X IMO.
I would really like to understand how is the notch cool. I am not trying to be rude but the notch and lack of Touch ID even if it was at the back are two main reasons for me not buying the iPhone X. I know it will definitely help in AR but that notch is right on the screen. Apple themselves have rules for app developers to not mask the notch so I am not sure they would ever do it in the future. If the phone is used in landscape mode with the notch on the left it will definitely block some text unless it’s fixed through the software.