I used to own an insurance agency in another life, so let me weigh in on this. :)
The insurance replacement value is the amount that it should cost to rebuild your home and replace your things in today's market. In most cases, your insurance agent is going to try to keep this on the high side of estimates, so that in the event that there is a catastrophic event, you have enough money to be "made whole."
The realtors and mortgage companies are not looking at the value of your things, or the replacement cost of rebuilding the home. They are only looking at the sales price that homes similar to yours have brought over the last few months.
If you have other questions, please feel free to contact me. You could also contact your insurance agent and ask for a recalculation of the replacement cost. That could lower the cost of your homeowner's insurance in the event you want to make a change (which I don't think I would suggest as a rule).