because atari developed and owns all of these games, as for nintendo not publishing huge collections, they choose not to. plus they don't own the rights to some of their early arcade games or so I've heard.
Remember sega, taito , midway, capcom, and snk have all done huge collections (shame snk and especially capcom struggle to remember they made games after 1993). Even data east made a solid collection on the wii. Blue Sky rangers does great intellivision collections now and again, activition has made a few great atari game collections. Probably others I'm forgetting as well. Nintendo hasn't because they probably think they can make more money charging 5 bucks for Urban Champion again. Konami doesn't because... well we all know how they operate these days.
I actually love those intellisvision, coleco, sega, and atari systems they sell every christmas with 100s of games on them.