Well that was very helpful wasn't it gekko?
There are always standard questions in interviews and that includes the ones checking your motivation.
As for charters - a good mix of destinations - some approaches which take more preparation and care but are satisfying to fly - passengers who look upon the flight as part of the holiday and are often flight fans - generally a change from the old routine.
All good reasons but if you get a better salary, don't be ashamed to mention that too. They will be pleased to hear it.
Good Luck,
FC.