Note that this kind of thing is one of the reasons why presidential elections matter, even in times when the pace of legislative change is frustratingly slow it matters a great deal whether the leadership of the country believes in the objectives of the laws that already exist.A couple of things to add to that. One is that this is one of the reasons that it matters whether or not the president is aggressive about appointing people to openings at all those departments and agencies. Another is that it matters whether or not the Senate gets around to confirming them. Yes, presidents can do quite a bit without legislation -- but it doesn't happen automatically. Bureaucracies have a very strong bias towards the status quo; presidents have to fight to make change happen, and when it's an obscure agency with low-profile issues, the bureaucrats often hold the high ground in that fight. Without a full compliment of presidential appointees, that fight may well become a route. No appointments; no confirmation; no change.
The other thing about this is how different the United States is from other democracies in the matter of political control over the bureaucracy. In Britain, no transition time is needed in part because so little transition happens -- the very top layer of policy-makers changes, but the bureaucracy remains intact. On the one hand, once that very top layer makes a decision, it can become law very quickly, and there are very few obstacles. On the other hand, there are all sorts of things, the things that never reach the notice of the very top layer, that really are not susceptible to democratic change.
Which gets back to the same point that I and other have made many times: Barack Obama should be far more aggressive -- and Democrats in the Senate should be far more aggressive -- about appointing and confirming people to executive branch positions.