Giving a player control of a powerful character is pretty much guaranteed to give that player a power trip.

It can be fun - after all, roleplaying is all about playing characters with abilities and authority beyond your own. So it's not a bad thing. It can be really great.

For the person playing the character with the power.

Transcript

Anakin: So I'm reinstated too?
Yoda: What have you done to deserve such an honour, young Padawan? Hmmm?
Anakin: I've deduced vital information. I think Dookû might be a Sith Lord.
Obi-Wan: Sith? But they're just legends.
Anakin: Remember, Yoda, you told Obi-Wan that fanatics are dedicating themselves to their memory. To use the Force for evil.
Yoda: That would be bad!
Padmé: We need to stop them!
Anakin: Exactly. And find if there are any others.
Yoda: Mmmm. Useful information this is. Reinstated you are.
Mace Windu: What? The Sith are rebuilding? When did this happen?
Yoda: Need you, we do, Master Windu.
Mace Windu: Just when I thought I was out... they pull me back in.