Simple customisation upload limits are too limited

The background I'd like to upload is 1.5Mb. The favicon I'd like to upload is 11.9Kb.

But the upload limits are set to 512Kb and 5Kb. I could understand these in 2003 but nowaways they seem impractical, and I don't want to create new branding materials just for this! As an example Twitter limit background sizes to 2Mb, that seems like a better choice.