I disagree. It was both a deterrent that just so happened to help put the Soviets on the road to fiscal ruin and a capable system that complemented the rest of our nuclear forces.
I believe that it truly was time to modernize our land based missiles, although I would have preferred they be on mobile launchers, but I think we agreed in a treaty not to field such capabilities, but I don't remember for sure.
There is a reason that over 65% of our strategic nuclear warheads are deployed on ballistic missile submarines. The boomers are mobile, survivable, ultra-quiet and carry an extremely destructive payload. The Trident D5 has the same accuracy that the MX had. 90 meters CEP. Land based missiles are in a FIXED position. Vulnerable to an enemy attack. There was a plan to put 50 MX ICBMs on mobile railway vehicles but it was canceled in 1992 due to the end of Cold War.
http://en.wikipedia.org/wiki/Peacekeeper_Rail_Garrison_Car#cite_note-8