And portable CD/MP3/VCD players are a lot cheaper than portable DVD.
SVCD looks like a format that's missed the boat, since it's less supported than VCD, but offers less compression than DivX/Xvid type codecs.
VCD, especially if made by a program which bungs a PC compatible player on as well, wins hands down in the compatibility stakes, playing acceptably on systems that are far too weedy to handle DVD or DivX (Divx is VERY CPU hungry, and generally lacks any hardware assistance)