Q. Why do people stand for the important prayers on Yom Kippur?
According to midrashic sources, Satan tells God he has no power over Israel on Yom Kippur. He says, “This day they resemble the angels. Angels do not eat and neither do they. Angels do not wear shoes and neither do they. Angels stand and so do they”.
Why then can we not be like angels for the rest of the year?
Because we are flesh and blood and we have an earthly nature and needs. We can aspire to be higher beings, but we still remain humans. On Yom Kippur we can spend a day as higher beings, and the experience certainly improves us, but it cannot last.
One day we might become angels but in the meantime we have tasks to perform on earth.