I love Raks. I do think that they belong to the category of monsters that are a little too weak for their listed CR but too powerful for anything lower than the current listing.
The arguments that "Rakshasa should never be caught alone" is a bit of a obfuscation; their CR is based on fighting one of them, not one of them and all their minions.
IMO, Raks should be played incredibly intelligently and incredibly selfishly. Another poster mentioned modelling them after the British colonials, and that's an excellent start. A Rakshasa that doesn't have a network of minions to do its dirty work for it is a sad, sad creature.
One of the things I love most about MMIII is the new breeds of Rakshasa. IMC, the Rakshasa culture is still primarily in Acheron, with Ravenna as their ultimate leader. There are several breeds (read: castes) of Rakshasa, all with different positions in society. For a Lawful Evil creature nominally based on Hindu mythology, it only makes sense to have a labrynthine bureaucracy of caste and favor that all hinge on greasing the palms of those more powerful than you and trampling on those beneath you.