So far, America has had a reasonably good record of reverting to less executive-dominant methods of governance between wars.
Congress did not declare war. However, their authorization can be seen constitutionally. They have authorized a reprisal. Since a reprisal constitutes authorizing a military response to a specific situation, then within the confines of that authorization, Bush has war powers.
Actually, it is more due to your poor education and ignorance of history.
Despite what the article states, FDR did NOT create military tribunals. CONGRESS did in the articles of war passed when WAR was DECLARED. FDR merely executed what Congress legislated. (see 10 USC 1471 - 1593, repealed)
No President has siezed the Legislative and Judicial branches as has Bush. None. Bush has explicitly done away with the right of habeus corpus. He has explicitly violated Article III of the Constitution.
He should be impeached.