The biggest problem is that Bush and his team improperly increased executive power and it was never seriously challenged. We're already seeing the effect of this, because it's already been announced that Joe Biden will have a major role in Obama's administration. Obama and future presidents can use the George W. Bush example to claim Bush's unconstitutional executive powers because it was never challenged.
John Adams (The 1st US Vice-President) said to his wife "My country has in its wisdom contrived for me the most insignificant office that ever the invention of man contrived or his imagination conceived." He joked that he should be addressed "Your Irrelevancy".
The Vice-President only has 2 official powers. He is the president of the Senate and he can take the place of the president if the president is incapacitated or dead. His Senate powers only give him the right to vote if there is a tie in the Senate. He can also preside over Senate hearings, but usually he is ignored unless he can cast a deciding vote. The deciding vote power rarely gets executed because tie votes in the Senate are rare. He wields no executive power officially and traditionally doesn't even attend presidential cabinet meetings.
Otherwise, the Vice-President only has as much power as the president decides to give him. In my lifetime: Hubert Humprey, Spiro Agnew, Gerald Ford, Nelson Rockefeller, Walter Mondale, George H. W. Bush, and Dan Quayle had almost no power while Vice-President.
This trend changed with Al Gore who was once the most powerful Vice-President in my lifetime (before Dick Cheney). Bill Clinton saw a capable man who wanted to work for his salary and it made sense to use his talents. The Clinton presidency was seen as Clinton being the coach and Al Gore being the quarterback. There was never any doubts that Bill Clinton was in charge.
When Dick Cheney became Vice-President, his boss gave him so much power that he was almost a co-president. Cheney was even considered the unofficial president of foreign affairs. George W. Bush gave little to no oversight over his vice-president.
Now Vice-Presidents are no longer seen as someone to fill in for the president if he can't make a social visit. It's unofficially a powerful post. This is good if the power isn't abused and the VP is clearly subordinate to the president. The problem is if a person wields unofficial undefined power answerable to no one, then it's close to impossible to challenge him. Even arguing about it is difficult because the power is undefined.