The high demands are due to the fact that owners in HBD allow players to become 6-year minor league FAs that never would in real life. As a result, the demands are based on ratings, age and experience.
We agree that it is very strange to see a 6-year FA asking for a contract in the millions, but it would also be very strange to see one player (6 year minor leaguer) asking for a minor league contract while another (major league FA) with the same skill set asks for $3M.
Players that would fit into the category of a true 6-year minor league free-agent (a player that is not a prospect and has exhausted his time with a franchise) ask for the realistic amount. As we add the Rule 5 draft in the future, we hope this will reduce these higher than expected demands.