No argument from me. I'd rather not have a pick guard at all, or have it come loose in the case for the buyer to decide. But if there must be one, it should either be black or preferably clear to allow the wood to show through. (It is truly criminal to put a pick guard over flamed koa). While pick guards are fairly easy to remove, there is always the specter of a tan line, even on a relatively new guitar.
I did remove a peeling pick guard from a then 16-year old 410, and the clearer parts of the tortoisehell patterns had left dark spots underneath, compared to the darker more opaque parts. I tried masking it off and using 35-40 hours of direct afternoon sun exposure, but the dramatic tan line was never going to match up with the top and the freckles never went away. I ended up putting on a black pick guard to cover up the whole mess before selling it.