First of all, I would heavily suggest you look for better sources than a .info page. If you're interested in Roman history, I would suggest starting with Livy's
On Rome. That should carry you up to the reign of Augustus. From there, Zosimus is a pretty solid source, and Ammianus Marcellinus is very heavy source of information. If you want a more digestible, modern source I can suggest you to a dozen sources that are more reliable than a .info site.
Now first of all, not all history sources are equal. Imagine if you got your history from the National Enquirer. Some of the things you're mentioning are about that reliable. But let's say that at least some of those debaucheries happened, and some certainly did. Under Emperors like Tiberius and Nero, the borders of Rome expanded. In fact, Rome reached its greatest extent under Trajan, who was well in that debased period you mention. Now I'm linking to a map of Rome during the Tetrarchy, shortly before the Constantine converted to Christianity and did away with the excessive sin. After Constantine and Christianity, the Western Empire fell within about 150 years. The Eastern Empire took a number of centuries, but it slowly withered into nothingness. Can you really blame the "decline in morals" when Rome was at its most powerful? Remember, it declined under Christians.
http://upload.wikimedia.org/wikipedia/commons/thumb/0/07/Tetrarchy_map3.jpg/300px-Tetrarchy_map3.jpg