We cannot see your contracts and there may actually be a clause giving up your right to a walkthrough.
I suggest reading your contractual agreements... If your agent insists there is no walkthrough, perhaps they can show you that clause, or lack of a final walkthrough clause.
I work in Lansing and hadn't heard that you don't do a final walk through before close. I would want to have a walk through as many things can change and a lot of different people may have been through the home.