You seem to be oversimplifying the issue, as though having some blowhard in power in the US making idle threats would have averted everything. It wouldn't. What Putin is seeking to capitalise on is the increasing diffusion of power in Western democracies. The people have much more influence over the decisions made by their leaders and the people (as a voting majority) have very little appetite for war. I imagine the voting majority in Russia have very little appetite for war either, but they are disempowered.
The US does not want to involve itself in another war: it can't afford to (which is why any threats would have been idle). The EU has no appetite for war. The majority want to move towards a post-war world. Continuing to respond to aggression with retaliatory or retributive aggression will never achieve that, it will just continue the same old cycle. Putin has no interest in playing by the rules, he is enjoying the fact that others have constrained themselves by rules which he feels free to disregard and capitalise on. He does not have the same accountability or scrutiny as leaders in Western democracies.
So a new way needs to be formulated to reign in someone like Putin, a way that does not involve bombing the crap out of a civilian population that would probably rather not have their leader stomping around trying to expand his legacy with no regard for the lives lost along the way. If you've got some great solution then fire away.