It must be simple
forget that there are just a few different jets in use (MD80, 727,737,747,757,A319,320,330,340) each requiring a crew certified to operate that plane, each with different seating configurations (is it better to inconvenience a select few or all passengers equally on an affected flight...how do you choose the lucky few).
Ok, so only get one that holds more than the max of any.
You're back to having to have crews sitting...you can't recycle because crews are specific to aircraft type.
And on the maintenance, airlines are required to carry a certain amount of spares for every aircraft of every type in their fleet. This is why most airlines pick a Boeing OR Airbus and stick. For some US carriers that have grown by glue this is a very large part of their embedded expense (like United for example). Too many different aircraft types make their maintenance operation very expensive.
I find it more amusing that you feel compelled to tell someone how simple it would be to "fix" their business without having the first clue about how it works.
I guess we'll keep each other laughing...
