As I see it, the main virtue of the
Java Bean conventions for
JSP are the ease of getting and setting variables and holding them over the duration of a session.
People do use them for business logic, particularly if it is simple database access, etc. but you don't want something that is going to be held in a session to be too big. Also be very careful not to hold system resources (such as database connections) in a bean that is going to last longer than a request.
Bill