That only the main plot. There are lots of other unrelated quests, un-marker quest, history to discover in the game. Same with the other 2 series. Sure if you do only the main quest it's over quick, but all 3 games were about the character's journey threw the waste land and his effect on it. Sadly that effect was cut from the ending of fallout 3, but in fallout 1/2 when you beat the game it told you exactly what happen because of your action with each city/civilization. Not just what happen in the main quest.
All of that is what I'm referring to as good for some anime series. The main story would be the search for father(Fo3), Finding water chip(fo1), find the Geck to save Village(Fo2) but along the way, the character would help stop raiders from attack shady sands (fo1), save a hunter from geckos (fo2), or stop a "vampire" problem (FO3).