Just because that may not of much worth to you, I'd hardly say it's worthless.
They are not much worth as game textures for anything else than saving disk space.
again, when beeing transfered to the GPU, the indexed stuff will vanish, they will either be 16bit or 32bit textures again like BMP and PNG. Just with the difference that you don't have used the full 32bit for color gradients so the filtering will suffer banding effects very likely unless you have a specific toonish style or similar.
That is what I meant with that comment and thought the clarification should be enough.
indexed colors in todays world mainly make sense for GIF + web
nothing else supports them anymore, especially not hardware accelerated 3d graphics like BlitzMax