A smite is an offensive single-hit melee attack and unique to paladins. They should be a core ability and used as such, not something you do once in a while. I'd like to see a paladin being able to smite every (evil) mob in a quest at least once. This also adds some prestige-independent dps that paladins could use very well.
Hence my proposal to make the following changes:
- Remove the Extra Smite enhancement line
- Make the maximum number of smites available equal to your CHA mod
- Lower the recharge time to 30s/smite