The insecurity stemming from the common cultural belief that the universe is hostile, that we are flawed and fragile, makes identification, as an apparent shield against change, seem tempting. But reality keeps changing - by identifying with things we set ourselves up for eventual loss. The body gets ill, ages, eventually dies. The car breaks down. Possessions wear out, or may get stolen.
Identification is too automatic, too subconscious.
The person who has to fulfil a promise may not be the same person who made the promise. But the main cost of identification is that a conditioned system of automatically available identities can hide you from the fact that you don't know your real identity, the essence behind these surface manifestations. But we are not a blank state on which culture can write as it pleases with no consequences to us. We also have a unique genetic and spiritual endowment, which will begin to manifest more as we grow, so we might dislike athletics and like walking in the woods, for example, or find Shakespeare boring but enjoy writing letters, or find physics pointless but be fascinated with maths, or search for deeper truth despite being ridiculed by others who believe what they're told. Consensus trance induction does have some powerful techniques, however.