I totally agree with you here, speed also plays a great role into this, but don't you think using SDK buttons seems a little too lazy?

Good design doesn't always mean as shiny as it could get. Minimal approach such as Windows Phone 7 UI design is also consider as a good design.

I understand what you are trying to imply here. I just realized that I also should have given some comparison on shiny and minimal designs as well. Thanks for mentioning about this. :)