The default is to install from the App Store or signed developers. That's not unreasonable and it gives you a error when it wont run. Googling the error message

The default is to install from the App Store or signed developers. That's not unreasonable and it gives you a error when it wont run. Googling the error message would give you several different options to run an unsigned app. The "new file system" as said earlier is 100% optional. You can use local storage the same way you did in 10.7. Yes you have autosave but for most users that's probably for the better.