That you can start it without having to push the clutch in is a good thing. All motor vehicles were like that until the lawyers started saying we're too stupid to be able to do that safely.
Being able to do that was an option designed in by the Jeep engineers that could be selected so you could use the starter motor without having to push the clutch in. Like you're in a hairy predicament (rolling down a trail, trail barreling down the track toward you, etc.) and you need to move the Jeep solely with the starter motor by leaving it in gear and with the clutch pedal up so the starter would move you as long as the key is in the start position.
Odds are good your Jeep's previous owner simply enabled that option for those reasons. That was one of the first things I did to my '97 TJ. If you really want to be forced to have to step down on the clutch pedal, even if it's in Neutral, simply insert a 20 amp fuse into the #20 fuse position behind the glove box. That fuse slot is marked Transmission.
Personally I'd leave it as is. Our parents, grandparents, and great-grandparents got along fine without having to step on the clutch pedal to start the engine when it was already in neutral. The lawyers have a habit of removing our ability to make our own decisions on such things.