Post script edit: Forgive me if i sound like ranting, i'm really not. I'm just looking at this with all the info i have (could be wrong) being as deductive as possible (again, could be wrong).

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 I'm not an American nor am I politician, please dont take this at face value. hehehe..

But from what i surmise, President Obama did what he did because of the ongoing "strike" Congress had on him. Remember how Congress rejected every Affordable Healthcare Act proposal presented by President Obama until it became the half-decent shit Obamacare is?

So maybe his line-of-thought at the time was that climate was more important than politics (I'm just guessing here!!!) and went ahead with it. Which i agree with your saying that he worked on it with almost a altruistic behavior. 

So for President Trump, he might do that to go right by Congress. But doing that has caused SUCH A BACKLASH on him, he got so much hate for it and i'm starting to feel some of it isn't even necessary at all. but what analysis has been saying is that he effectively ceded Global Power by rights of being Climate Conservation Leader for the benefit of businesses and taxpayers in cost saved.

But there are better ways to save taxpayers money and jobs IMHO. Greentech is a booming industry. Solar itself supports more jobs now than Coal is and numbers continue to rise. And dont get me started on Military, I know the US has to keep Its Military at top notch levels by spending one-fifth of Federal Budget, which is something akin to 12 thousand dollars of taxpayer money PER AMERICAN. I totally understand it's to keep America as a Global Power but then wouldn't it be ironic because President Trump effectively ceded some American Global Power through the withdrawal.

I'm just being hypothetical... again.. i can totally be wrong and i understand that.