This is a good point but: (1) what happened was considered unthinkable by many, (2) the wold has changed which allowed those sanctions and (3) the idea was not to 'rock the boat' and saying if you do this we will do that could have allowed for the Russian side to plan better playing into their hands and might have encouraged them to start a war.

So this is easy to say now, but I don't think there would have been any takers for this three weeks ago when for instance Germany was still firmly in the mistaken mindset that all of this is so unlikely that they don't need to prepare for it at all.