You are not looking for a "retail" or "full price" buyer with a house in this condition. You're looking for the equivalent of the clearance shopper. :)
That really bothers me. Aside from the roof, the house is immaculate. It is brand new.
I'm sorry if my words were offensive. That was definitely not my intention. :)
However, let's take a look at what happened here: I assumed that because the roof was in bad shape, other things in the house were also in bad shape. This is what will happen in the mind of your garden-variety "retail" house shopper (who will almost certainly be using a mortgage to buy). As others including your realtor have said, if this is the market you want to sell to, you will need to fix the roof, or they won't even get out of the car to come inside and look at the condition of the inside.
But your "clearance" shopper--that is, an investor or future landlord buying with cash--will be able to see the roof for what it is, and will have the "eye" to know the condition of all the other major systems (HVAC, plumbing, wiring, foundation). That kind of buyer will be experienced in doing the math of the overall purchase price and can offer accordingly.
In my world, it would be like shopping for a pair of pants on a clearance rack. If the hem is ripped out of one leg, I know I can fix that myself with minimal effort and would certainly buy them if the price is right; a ripped hem would not scare me off. But if it's missing a zipper, or has a huge rip in the fabric, I would know it would be out of my league to fix and I'd pass. I'm a "clearance" shopper in that regard. But many people don't want to be bothered with hemming a pants leg, and they just want something "perfect" and "new."
What it comes down to is this: do you have the TIME and the MONEY to fix the roof and attract the retail buyer? If so, do it. If not, put it on the market as a cash-only as-is sale.
A compromise might be to put it on the market now as a cash-only/as-is, and then shop for roof quotes while it's on the market. You can always take the cash-only listing down and re-list as a retail property after the roof is fixed.
Good luck!