in the manner that we removed Gadaffi, the whole of Syria would now be under IS rule?
As Libya is now under IS rule, you mean?
Nobody has ever suggested removing anybody - a proposal was made to send assistance to the rebels on humanitarian grounds - that proposal was voted down and nothing was done.
Isis leapt into the gap, recruited supporters from among people who were fighting Assad and rose from being an unknown fanatical entity to a world threat and we are now involved in fighting in the Middle East, with Assad as our ally.
The alternative to doing nothing in countries that wished to modernise during the Arab Spring revolts was to leave those despots being opposed where they were, which is what the west decided to do, and never had any real intention of doing anything else - bad business otherwise.
As I have always said, if oil had been a factor things would have been very different.
http://www.thedailybeast.com/articles/2014/07/07/u-s-assad-s-machinery-of-death-worst-since-the-nazis.html
jIM cARROLL