I have bought an Xbox One to play Call of Duty: Advanced Warfare, and now my little boy also want to play Minecraft game. So I go to add a new profile, but it requires to add a new email address for the new Microsoft account. I only would like to have offline profile creation and earn offline achievements and it seems to be no option to do that.
No, the Xbox One lacks of the ability to create an offline account. It is good idea to have online or offline profiles of their own to play on a single console. However, you can not do that since now. You have to create a new accounts for your kids because everything such as progress, saves and purchase licenses are link to Microsoft account and Gamertag. If you want to prevent them from unlocking achievements or cheating the system, the best way is to add other profiles as family members and use the parental control feature.
Most of Achievements are linked to the Xbox live cloud and only a limited amount offline, so Gamerscore can not modify the game data files to unlock them. For users who have paid the gold subscription, each profile is potentially a Gold gamertag. Everyone should play online games to get the own achievements and stats by themself.
In the addition, it is annoying that my friends to use my gamertage for play PowerStar Golf or others. I am able to setup each offline account for my friends on my Xbox 360.