The trace tool in SQL Server is mostly used to find performance problems related to SQL Server. But it is also a great tool to find performance problems in application servers and web servers.
The general way of thinking is this: Even if your SQL Server is doing fine what impact does the information flow have on other parts of the system? It is not unusual that the SQL Server is the most powerful machine in the system, allowing it to cope with huge loads of requests.
If you see either large amounts of requests to SQL Server or fewer requests but with large amounts of data try to figure out how the application manages this information. The life of an application server is not that simple, by knowing the SQL Server requests you can figure out what it is doing and maybe make it easier on both the application server and SQL Server.