I concur. Would you believe our landlords at our new place were adamant about us NOT painting? The husband is a sheet rocker, so he said he hates the thought of crappy paint on his walls. I understand that, it's just ironic that I planned to take time off from work to paint, and now I can't. Managed places typically don't care if you paint it back to the original color when you leave.
That sucks, painted rooms make me feel happier than boring white/cream.
Your landlord probably doesn't like paint because it's harder to cover up the bullet holes.