I think when some people do have complaints about Nyepi, it's more to do with the restrictive nature of the rules imposed on them during that period. It can often feel like being a prisoner in your own home.
Bali tries to promote understanding across cultures, but often only when it suits themselves. They are happy to receive tourist dollars but to try to give the illusion they are still in control of their own culture, and not corrupted by all the outside forces of greed and mass development, they often impose some unreasonable expectations. I guess this is fine if they wanted to cut themselves off from the rest of the world, but they don't do they? They are actively encouraging more foreign visitors.
To shut down the international airport, along with radio and TV broadcasts, also cutting electricity (PLN) supply for many areas, may be a little overkill. I mean, has it really improved the spiritual standing of the Balinese community? Has it stopped crime? Improved honesty? Cleaned the beaches? Fixed infrastructure?
@Shorty, non of the holidays you mention include marshall law, you are still free to leave your own home if you so desire. But yes, people who use such a strong word as "bullshit" are pushing it.
Nyepi can be fun if you do enjoy solace in your own home, or the chance to spend a relaxing few days in a hotel. I've done both and both have been an adventure. But I'm sure a simple tourist on a 5 or 7 day holiday would prefer to have that time spend at the beach, shopping or exploring out and about.