While a good idea, there are a series of logistical nightmares that would have to be solved first. I had a similar discussion during a class once, and we came up with a bunch of questions, and little in the way of answers.
1. Who is in charge, and runs them? For that matter pays for them? Does local emergency management run them, or does Local LEO, State LEO, Fire? How do you handle/pay for training for the use of generators, and lights? Who repairs them, and maintains them? Do you have a roster of people who are scheduled for shifts? How many back ups do you have per "shift"? When do you activate people?
2. Are they in a fixed location, or do you store them in a central location? If you have them in a fixed location, how do you secure them? If they are in a central location, are they on flatbeds, or small trailers? Are personal vehicles used to tow the trailers, or are city/county vehicles? What type of DL requirements/training to tow them? Where would you set them up? Does the city/county have land to park on, or do you pay a farmer to use field. Will housing areas want them nearby due to noise/light?
