I disagree. Data lock-in is flat-out evil. Proprietary formats and stores are fine, but everything needs to let data back out in open formats. Every app shou

I disagree. Data lock-in is flat-out evil. Proprietary formats and stores are fine, but everything needs to let data back out in open formats. Every app should have some sort of "I'd like to take my ball and go home" bulk-export. Because no matter what you tell users up front, they won't read it. Most people simply assume reasonableness. Pretending otherwise is just seeking to take advantage of human nature.