I agree that visual identity is important and it's better to have a custom design to stand out from the crowd, but one thing you haven't mentioned are Bootstrap

I agree that visual identity is important and it's better to have a custom design to stand out from the crowd, but one thing you haven't mentioned are Bootstrap themes - there is already a wide variety of themes to choose from and most of them change the look&feel of Bootstrap drastically. I think it's a fair compromise between having to create custom design (which can be time consuming) and using default Bootstrap theme (which is overused and doesn't stand out).