Perceived problem: People (kids, siblings) getting into your worlds and messing about
Perceived solution: Ability to add a password to your saved game
Currently, I enjoy playing Minecraft with my 3 year old son and 6 year old daughter. We have fun exploring, building, hunting creepers, etc. We have numerous worlds that they enjoy playing in and building the craziest, strangest things in all sorts of haphazardly.
However, I have a 'main' world that I'd like to think of as "mine" where I go to unleash my inner OCD and perhaps make a megaproject or 4. They often get in there and cause all sorts of havoc digging up farms, placing water traps in the middle of my projects, etc. While I don't necessarily mind it, it does get tedious time after time after time. My 6 year old is good about not going into Daddy's world but my 3 year old doesn't know which is which and my wife isn't much of a gamer.
The only other option I could think of would be to make some kind of batch file that simply moves the saved game folder around before and after I play.
I guess I should have said the "option to password protect your games" instead of implying that each and every game should have a pw.
Reader Rabbit, Arthur's Reading and the like of pre-K, kindergarten and even first grade games have did wonders for my kids' education (on top of us reading to them regularly and playing different edu-games in the car when we travel) , I see no reason why they can't learn from playing games as entertainment on the computer as well.
seriously, this has nothing to do with minecraft specifically . . .
if you're on windows create a new user and install minecraft only for that user and password protect that account. No need for this.
OR teach them it's wrong -____-
EDIT: yeah, looking back at your post I see that won't let you play with them when you want to. So maybe you might want to create a shortcut to your save folder and move your file in and out of there when you want to play it. Or deny the folder read/write privaliges
The suggestion itself isn't bad, like guns or obsidian tools or "wool armor", but it's necessity = zero. If you don't want your kids on your world, tell them not to. If they do, ground them. Still do, ground them longer. Still do, get out a broom. (Just kidding)
I agree it's not a terrible suggestion in and of itself, but there are lots of cases that can be resolved with this or that implementation in the game. Similarly, they can be resolved by the user's ingenuity.
Nothing wrong with suggesting them, but some things are such low priority, and affect such a small user base, that people can take it upon themselves to resolve it or request a third party to implement it.