Even some divisions would get more viewers than others. The AL East (which would probably be the most requested) would probably get way more subs than the AL Central (which would probably be the least requested), with the NL East, NL Central, and NL West in the midddle. At the same time, the highest and lowest marketed teams lie within these respective divisions. Even if the moneys are allocated to each division and/or team equally, there is still a disparity when it comes to marketing and advertisement.
I am not saying that your idea is not a good suggestion (in fact, as a sub, I like your idea); I am simply saying that MLB would not allow it for the reasons I stated.