If I release an open-source project with a logo of a little horse, and don't trademark the horse, then someone else can use that horse, completely separately from my project, to represent another project that has nothing to do with mine, and thus dilute my project's brand. Is there any way to reduce the impact of this without closing the source to the artwork?
To clarify: (1) Your scenario = don't trademark, use open source license. (2) What Mozilla does = trademark, use proprietary license. (3) What Mark thinks should be done (afaiu) = trademark, use open source license.
I don't know a good way to reduce the impact in scenario (1) through legal means, but if you are worried about this, why not choose scenario (3)?
