Why are most denominations defined by theology and not ethical/practical differences?

Isn't the point of the life of Jesus to get us to change our hearts and change our behaviors? Shouldn't then the main defining feature of denominations be essentially to what degree you are asked to love? To renounce this world? To the ethical standards you are held? So e.g. a certain denomination might be defined as people who say they believe in the message of Jesus, sing some songs, eat/drink some food, and go once a week. Another denomination might be defined by being of believers who don't eat meat, are pacifist, share all possessions in common, shave their head/beard, and refrain from 300 other nefarious practices, all while partaking in a high church style liturgy 3 times a day and spending at least 3 hours a day in deep centering prayer. In these example denominations, what really defines them is their behavior. Their behavior is downstream of the love, renunciation, peace, joy etc. present in their hearts. But you really don't need sophisticated beliefs to get your heart right. You need to change your desires and your behavior. So again, why are so many denominations defined by abstract, metaphysical matters of theology? Why aren't they defined solely by the behaviors and the desires they are aiming to cultivate or relinquish? Jesus was no theologian. Jesus was a man of action.