It’s also because so much of what Obama did he did without laws. In some cases he had legal authority, and made ill-conceived use of it; and in other cases, he just made stuff up. Stroke of the pen can be crossed out.
Give Congress grief for lack of action, but there are also many places where it was better to repair things administratively - at least initially.
Right, like when Trump started enforcing the law on DACA people, a class created by Obama's pen stroke decreeing that he'd use "prosecutorial discretion" to refuse to enforce the law, giving them de-facto amnesty. Well, until a court said "nope, you are required to permit them to break the law, You may not enforce the laws of the land." The court just takes Obama's pen stroke carves it into stone and we have new law, all without a single vote being cast by citizen or representative. In other words, the illusion that we are in a representative republic is starting to dissipate.