Indeed many improvements are needed. The major mistake at UnionStation was obliterating the oldconcourse/information kiosk with the skylights to build an anonymous office tower. In truth that tower needs to go away so that ALL of the platforms/tracks can be come run through. with the concourse above. Eliminating the excess supports for the office buildings will open up space on the train platforms.
If they re-design the existing baggage platforms to become high level, the roll on, roll off from standard single level trains will become more convenient all passengers.
As to routes south, using Rock Island to Joliet is brilliant. A combination of Metra Electric/South Shore as far as South Bend reduces NS's ability to delay Amtrak.