The only game I can think of that handled this was Mount & Blade. In that game you just saved every time you exited the game (I guess MMO's are like that too).
Might not be the option I would want for this game, but it's one option.
You could save anytime in mount and blade, with one requirement, you could not save during battles only on the map page.
Mount and blade has a map where you and other groups move around in real time. If you come close to enemies you enter combat modus. where you ride around and fight the enemies in first or third person together with your army.
Saving in combat modus is not in as the game would have to save all the data to recreate it and it's made by a very small company. It also kind of pointless as combat don't last that long.
Elder scroll games don't have different modus like this if you enter a dungeon the game has to save everything in the dungeon anyway as you might leave and come back later.
Save points evolved the same way as no save during combat in M&B, All games was based on levels you completed and went on to the next one, to save room on the small memory sticks and to simplify coding they only let you save at end of level so they only had to store current level, inventory, player health and other stats. 20-50 bytes instead of many kilobytes.
Before you could save at all you had level codes you could write in to jump to last level.