It's true that many of the alternatives lack certain features, but most PDF files don't use those features either. You can use a simpler reader except in cases where you need all the features.
What about those of us who don't update because we're too lazy?
You might be lazy, but your computer isn't; it's been sending out spam 24/7 for a while now.
And if they still want to be dicks after that, make it two weeks, and say that you'd prefer not to get attorneys involved, with a bit of stress on the prefer.
Wikipedia has a reasonably easy-to-follow explanation of how this works.
Thus spake the master programmer: "After three days without programming, life becomes meaningless." -- Geoffrey James, "The Tao of Programming"