CA, we do not pasken from a maaseh rav. You do not know why they left. Rambam gives four heterim (HIlchot Melachim 4:9). As for the gedolim who never lived here, they have a different cheshbon. because of their communal duties.
Uknowwhatimsayin, you are correct but a person must also ask if he really needs to maintain a high life-style. I heard of someone who went back (decades ago) because at the time Israel did not have cream cheese! In addition one must take into consideration the lower costs here, particularly in education.