Part of the reasoning is simply the layout of the nation's electrical grid--the "high-side" voltage varies from area to area, even within the same state. I currently work at a 800 MW combined cycle plant here in Ohio, and our high side voltage is 345KV (345, 000 Volts)--some other areas run between 230KV and 700KV.
As it is distributed down to the residential level, it is stepped down through numerous transformers--the high voltage (230KV and up) is necessary for long distance transmission (think of the voltage as the "pressure" pushing power down the line)--in order to tap into the electrical system at a local level, they would have to do one of two things:
1--have a bunch of different generator units on hand to match the various incoming voltages at local substations
2--have a bunch of small medium voltage (480 V) generators that could be hooked in at numerous locations on the "low side" of the local substations

In short, it would be a logistic nightmare

One thing that actually helps when they are trying to get back on line is for the load to be removed--typically they will disconnect everyone in order to get the plant back up, then start slowly restoring power to the public; this keeps the reactive load on the generators in a happy spot, and keeps them from overheating.

Don't know where you are located, but if you're in an area where they rely on either coal, oil-fired, or nuclear plants, it can take a few days just to get the plant restarted--that may be contributing to your delay. I don't have any experience with those type plants, as I work at a gas turbine powered plant (jet engines--we can be making power within a half hour)

Good luck getting through this mess--hope you get back to normal soon

Jim