Seem to be at a standstill with my experience and level. If I was to gain 1 XP per 1 coin I was to earn on Idle-Empire, I would have more of an incentive to earn coins.
Could also induce a greater sense of progression and enhancement for my account.
This progression is also what enables people to become addicted too so this would be beneficial as many more users would be more active just in order to have more XP.
In addition to this, I believe you should be able to click the XP badge and have a basic leaderboard of all members based on XP, this could maybe make room for some competition and overall competitiveness amongst other users bringing an even greater intensive to grind IE.
Just my opinions however.