In a car showroom,
“I like the car, but can you make the front door slightly bigger” said big-size lady to the car salesman.
Though the car maker would like to listen to every suggestions, but sometimes it’s just not possible to please everyone. Hence, compromise is the order of the day, simply because some suggestions are just not plausible due to the cost of customization.
This happens to a lot of open source system such as WordPress, Apache, etc. These systems are developed by combining effort from developers around the world together with valuable feedbacks from millions of users.
The default color for WordPress admin is blue. Why blue? That’s because a blue background works best with web browser default colors for hyperlink.
Don’t change it to green just because your customer’s favorite color is green!
I absolutely agree with your last paragraph ;)