The redskins have a deep and loyal fan base. The redskins won multiple Super Bowls in the 80's and 90's. Changing the name would damage their brand and legacy.
No one cares about BP. They've won nothing. John riggins didn't carry BP to a Super Bowl win. Doug Williams wasn't the first black qb to win a Super Bowl for BP.
You're comparing apples to oranges. Please provide another major sports franchise on the level of the Washington redskins that changed their brand name and continued on with success.