It would also be a place devoid of a critical audience - nature the setting, animals the focus, the rest of humanity well away - and the ranch would be a place from which they could to some degree keep outsiders. no Aguirre with his binoculars, no pickups driving past or neighbors with curious stares, no wives urging them to work harder at the family business or get a better job.
Ennis's father was clearly a man of strong opinions, which he tried to impose on his sone; Jack's father was controlling and disapproving. On their own ranch the two of them could create what they wanted, free of the constant evaluation and criticism of others.