This is usually a phenomena associated with RPGs...where you can only have a single save file per system account.  Trying to start a new file on the same account gets a message similar to, "There is already a save file detected, saving/creating a new file will overwrite the existing file..."

Why?  Why is this a freaking thing? 

Dont know about anythingother than Pokemon but i think for Pokemon's case, the first games were limited to it. After seeing sales and minor complaints, GF decided to make single save file permanent in every installment.

Dragons Dogma is another good example

I have the same problem with Steam games. It's annoying on consoles as well that I have to make a profile for my kids instead of simply saving to a different file.

Is Dragon Age restricted to one save too now? I usually like to play different files with different paths next to eachother. I had 3 parties on the go in the first one, and ended up with 4 paths going at the end of the Witcher 2.

I´m having a similar problem with Smash Bros for wiiu, i bought the game with my brother but we play in the same save file, we  can´t have two, so all the things he is getting on the game i don´thave to get them anymore, that´s annoying, the game is still being great, of course, but that´s a meh thing.

If I remember correctly, a few or all of the souls games did. One save file per character, I believe. I think there were several reasons for it but the main one was so that you couldn't just reload a save after you died or made some choice that you didn't like. It made each action you took mean something. It's in spirit of that kind of game.

Dragon's dogma is the only other game that I can think of that had only one save file. Basically, its the same as the souls games but there's two new things. First, your pawns are tied directly to your character and any rewards it gets while in other players' worlds. If you delete your character, you would lose the pawn. Any DLC you bought was tied to that save file, you lost that save or deleted, you would lose the DLC. If you wanted to start a new character, you would lose the save file and any DLC that was attached to it. That was pretty dirty for a company to do in my opinion since a lot of the players made new characters after a while.

Pikmin games only had 1 save file, same for Sonic Lost World

It's funny in Lost World's case because Sonic 3 & Knuckles, the first Sonic game with a save function, had so many save files!

Dragon's Dogma wants you to prevent exiting the game in case you fucked up. If you fuck up, the game will automatically save and you won't be able to do nothing to fix it unless you:

a) beat the game, start over again.

b) completely erase your save file.

Capcom took some cues from Animal Crossing :P

Wouldn't it be one save per character instead of 1 save at all then ?