Is feature to customize themes and colors for Mobile/Web Apps important for UX?

We are building a CRM like application but targeting micro businesses, consultants and etc.

While designing UI for our Mobile/Web App, my manager suggested us to inlcude themes, color and fonts customization so our users will be able to customize the look and feel of the App.

From my Point of View, I feel this is rather pointless, I don't think users would care about theme customizations. To further my point, Facebook, linkedIn, or Whatsapp doesn't have it....

So my question, is the feature of customizing themes and colors important for a good UX experience?