Why do you think presidents, in recent years, have given vice presidents more responsibilities?

Because all the presidents care about is there reputation unlike in the past where they actually try to make a difference now all they care about is looking good in front of a camera and since the Vice President isn't that famous they give them all the work anyway they don't need to keep up with there reputation and looking good in front of a camera

In most cases, he picks someone whom he can trust and work with. Therefore he's willing to assign him important missions.