Spouse and I are the kind of open-house junkies who can walk into a place and see its potential... and of course the things that are screwed up. We can appreciate the layout, the walls & ceilings, and the things that are difficult to change. Decor is just decor, it's not as hard to change, and the crappier it looks then the better for us as potential buyers.
What we've learned, though, is that we are in the microscopic minority of open-house visitors. The vast majority of the HGTV generation cannot see the potential in a place. They can't visualize what it would look like with granite counters. They can look at a granite counter and decide whether or not they like it, but they don't want to have to look at Formica and think about how it would look in granite.
So not only is "do nothing" not an option, but a decorating allowance is not an option either. You can do what the realtor suggests and make it attractive to a high percentage of the viewers, while charging them a higher price for having done the upgrades, and with less time/hassle.
Or you can wait a long time for the one customer who can see the potential in the place, and who knows enough about what they're doing to lowball you. I think the time/hassle will outweigh the potential savings of not doing the upgrades.
We're much happier with Corian too, and it doesn't need maintenance.