I grew up there too and yes there is a serious problem with the raised section from Adams Street to I-690.
I agree it’s ugly and a maintenance nightmare. However, the elevated railroad bed that is now I-690 from DeWitt out to Solvay is not much better.
The Thruway going through the city when it was built was not an option as that was not part of the Thruway charter. Yet ththe city wanted some sort of interstate from the city center to the suburbs in the north and access to the south.
They really only had a few options.
1) What they did.
2) direct I-81 easterly at Tully and bring it up through Jamesville where I-481 is now.
3) direct it through the Onondaga Indian Reservation and go up the west side of Onondaga Lake.
As it is they drew as straight a line as possible from Cortland to Watertown and followed the natural topography to minimize construction costs.
They elevated it to not destroy the city with a distinct no-cross line like there is with East/West railroad line.
Yup, I understand why they did it as they did.
The problem, as I approach half a century in age, is that advocates of large-scale projects which are defended with “it will last for decades!” don’t appreciate how short “decades” is, and the hideous cost of overhaul when “it” starts to decay in earnest thereafter.
(I’m implicitly including I-690 and any other related elevated transport when referencing I-81 within Syracuse. All part of the same crumbling skeleton.)