I inherited an app from someone a few years ago at work, and for whatever reason, the developer loved a gray themed UI. Gray buttons. Gray text entry. You never knew what was disabled and just gray for fun. Needless to say that changed...
Am certainly not the dev you inherited the project from but I used to prefer an all gray palette too on projects that didn't afford me any design help.
This was because I'm colour blind (red green) and find it near impossible to keep track of what signal I may be sending using one of the other colours while I am likely oblivious to that colour even being used.
So I used to use an all gray palette as a placeholder till real designers who could properly see colours and understood significance of each could come in and "colour in" the UI.
