Functional Obsolescence...How Far is Too Far?

Functional Obsolescence is one of my favorite terms in Real Estate. Landlord.com describes it as:

Functional Obsolescence: Functional obsolescence occurs when a property loses value due to its architectural design, building style, size, outdated amenities, local economic conditions and changing technology.

The question is if someone is living in a house that is functionally obsolete, How Much is too much when it comes to making changes. In a Sellers market, a sellers point of view would be that it is the buyers problem. as long as we can sell it, the buyer can do anything they want to it...even tear it down. In our current buyers market, we may need to see more creativity on the part of a seller.

If removing a wall in the house opens up the entire space, is it worth it? If changes could be made for let's say, $10,000, isn't that a figure that most likely would be taken off of the sales price anyway?

Clearly we are talking in generalities as every house and floor plan comes with its own set of challenges but isn't it worth taking a look? We know that cosmetic changes affect the appeal of a property both at the curb and inside so if a seller takes that to the next level, wouldn't it make good business sense?