Your question is based on questioning the validly and correctness of the users request, and your manager's choice to accept it and have it actioned.  The user's request is valid, and your manager's decision is valid.  

**This is the work you are employed to do**.

What you are being asked for is the implementation of a non-functional requirement.

You are being asked for a usability improvement, not an expansion of functionality.

**Non-functional requirements of a system are *still* requirements**.

In this case, these usability fixes are intended to increase the user's productivity and lower their error rates.

Usability fixes can be non-trivial to implement.  This does not mean they should be dealt with as second-class concerns.  As a developer, you are there to create what is *important*, not what is *easy*.

An excellent book for helping understand usability as a key, core, engineering concern is  
<a href="http://www.jnd.org/books/design-of-everyday-things-revised.html">"The Design of Everyday Things" by Donald Norman (link)</a>. 

A good example of a system which is feature-complete, and which needs further development of the user controls, is the Model T Ford.  As a car, it goes. It steers. It stops. It carries passengers.

Now <a href="http://www.caranddriver.com/features/how-to-drive-a-ford-model-t">take a look at the user controls (link)</a>.  No-one makes them like that any more - for good reasons.

They are hard (and error-prone, i.e. injury-prone) to start.

The throttle is a pair of sticks on opposite sides of the steering column, and they have to be operated independently and, at times, simultaneously.