Can my site's administrators bypass required profile fields during user creation?
The only easy way I can think of is to make this fields not required. Then the admins can leave it empty.

I'd just let the Admins enter the extra data, even if you don't really need it. Admins are specially trust worthy users. It's not likely that you have a lot of them.

If you must: Create your own form using Drupa FAPI and create a new user by calling user_save in the submit function.