Because Bob......all phases of flight have critical handling aspects. Careful analysis can reveal the important skills and parameters that need to be tracked and monitored. Comparison with other aircraft/systems may reveal other considerations that need tracking. Just look at the Handling Manual, the ODM, the FRC's, the Abnormals etc... Now, Take-Off is a very dynamic and historically risky event. Even a FJ has a considerable amount of critical handling on Take Off (even if you don't think so). Some of the most critical factors on Take-Off are weight, configuration, engine performance and handling. The handling includes rotation initiation speed, rotation rate, Alpha and pitch attitude(s). Individual types may have additional Take-Off handling specifics.
OAP