Load of nonsense.
Every single one is more or less the same:
-Weak backstory introduced
-Love interest introduced
-We see some hard times for the main character
-Insert some awful one line jokes
-There's a huge CGI fight
-The bad guys look to gain the upper hand
-Love interest is captured and / or dies
-There's another huge CGI fight
-Good guy wins with the possibility of another bad guy emerging to make some more money for the studio in the form of a sequel
-The End.
These films are normally just a money making scheme at the expense of any artistic integrity.
They should be filed under the same category as 'Coldplay' and the last 2 seasons of 'Friends'. These films are lapped up at the box office because they translate to the lowest common denominator.
This is pretty much the thought process behind them.