This is employer-centric in my opinion - sure you're not paid to write code, and sure you can reuse existing code base in new and exciting ways.

But - there's also value in learning new things, in new skills, in new toolsets. Maybe it's not best for the employer, but for you the employee it can help quite a bit.

There's a fine balance - ideally your employer encourages you to learn things on the job, and to try new things that may not necessarily make it to production, but improve your skillset overall.