Unsolicited redesigns and design commentary | TechRepublic:

There are valuable design insights to be gleaned from these sources. Seeing a different solution to a problem can spark new insights and new designs. Commentary can also spark useful debates about particular approaches and aesthetics.

That said, visual design is only an aspect of software design, not its entirety. UX designers also have to help make decisions about affordances, functionality, trade-offs, business decisions, and monetisation.