Complete log files are amazingly useful. Consider a situation where your application is deployed somewhere like a bank. You can't go in there and debug it by hand and they sure aren't going to send you their data. What you can get is a complete log which can point you to where the problem occured. Having a number of log levels is very helpful. Normally the application would run in a mode such that it only reports on fatal errors or serious errors. When you need to debug it a user can switch on the debug or trace output and get far more information.
The sort of logging you're seeing does seem excessive but I can't really say it is for certain without knowing more about the application and where it might be deployed.
