poita said:

On old transfers of cartoons, it was pretty common paractice to do a vblur on them as part of the transfer to thicken up the lines to stop them 'thrumming' which was a line ending up on only one of the TV scanlines. Due to TV being interlaced the cartoon lines would appear to jiggle or blink in and out, so various blur methods to thicken the lines up was pretty common.

That seems to clarify things a bunch. Similarly I'm thinking the trend towards duller whites is because most modern TVs are LCDs set to some uncalibrated bright mode.