Jamie Foxx should receive praise regardless. That was a very heroic thing that he did. If anything, people are wanting to downplay it because he's a famous actor. However, being a good person, putting others before yourself, putting yourself in harm's way...that is an amazing thing, and he deserves all kudos. I'd rather he get TOO much praise than not enough.
Famous actors are just ordinary people who act for a living. They don't have to be particularly good at what they do to become famous. So they are doing nothing more, or less, heroic than a normal citizen when they save someone, and I think everyone who does something heroic should receive the same praise. Fame doesn't make anyone better than anyone else, it just means more people know who you are.
Doing the right thing should always be expected and praised. However, celebrities should not be praised more than an ordinary citizen for an act of heroism. Just because someone is a public figure doesn't mean that they are more deserving of accolades for a job well done than an average person going about their day is.
Famous actors are famous. They receive more attention for everything they do - good or bad. Therefore, when they do something good, they will receive more attention than the average person, and if they do something bad, they will also receive more attention than others. It's a two-way street. Obviously, in a perfect world, everyone would receive equal attention for equal actions, but this is just the way it is.