As they said, Comcast has pretty much always had that limit.
If you were seriously downloading 250 GB or more per month, you probably would have gotten a notice from your ISP telling you to stop, threatening to terminate your service. It's happened to a couple of my friends when they were torrenting day and night.
Now it's just official, and it's FAR more than many other countries' ISPs allow. I think a lot of UK ISPs limit to 40-60 GB.
When the internet gets faster, with fibre optics and such, and if the average user uses more bandwidth, they probably will raise the limit.
Related to digital distribution, I don't see this as a problem at all. The biggest games on Steam right now are still under 10 GB I believe...most large games are closer to 6 or 7 GB. And I don't know anybody who's going to download 30 full-sized games in a month in order to get past 250 GB...that's a Half Life 2 or a Call of Duty 4 download each day for 30 days...no.
Good points. Also, playing games online uses very little bandwidth(unless the coding is poor).