I notice that vroom explicitly stated the limit would be 80kb in his announcement of the feature, Home Node Image. He did not give a justification. I presume it was some combination of (a) keeping database consumption to a reasonable limit (80kb is by itself larger than the maximum size of a textual node); and (b) a guideline that an avatar or profile pic shouldn't need to be large, perhaps based on (c) not overburdening the download bandwidth of users. These all seem reasonable to me.

Note that the limitation is only imposed at upload time; the database field storing the image data is actually limited to 16Mb, so we could theoretically put a larger image in the database than 80kb. Feel free to submit your reasonable supplications to the gods via /msg. :-)

Also, if monks would like to argue that the limit should be something higher than 80kb, please discuss here. Thanks!