No.

It's interesting, because I would say that to some extent the renovation may be of higher quality than the original build because the post-war 1940s to the 1970s were not particularly a high point in construction, and the house is often worth so much more as property than when it was built--but as far as creativity, usually not so much. Pretty generic white and grey modernism with the odd subway tile and antique-looking faucets here and there.

This house was restored utilizing correspondence between the architect and original owners, so the renovation was strict:

http://www.estately.com/listings/info/3303-cherry-lane

How much do you think you could do to this house before it was no longer itself? This house is pretty much all original fabric. The furniture is staging, and even though it's appropriate it's not 100%. 1959 would have presented differently

I don't think furniture is necessarily crucial to the architecture, but it still alters the spirit somewhat:

http://www.estately.com/listings/info/4745-girard-avenue-s--1

Neutra was an acknowledged master architect who designed in the Modern idiom. I'm not exactly sure what you are asking, but it would certainly be possible to remodel the house keeping to the Modern vocabulary and Mr. Neutra's intent.

That said, it would take an experienced architect to bring it off, and remain true to Mr. Neutra's design, not to mention sustaining the property value.

Credit isn't given for the house in the second photo, as far as I could tell.

FWIW, I am always skeptical of the language used in real estate listings.

I think the other thing is that it depends upon how "significant" the architecture/architect is...

Farnsworth House (as unliveable as it is as a house except maybe for a day or two occasionally) is a masterpiece and it's such a complete expression of an idea that something out of place "ruins" it.

There are several Usonian houses on the market, both landmarked, and some that may be "in the style of". Many of them have newer kitchens and baths because 60 year old kitchens and baths can be problematic and Wright's ideas about kitchens and baths were pretty minimalist.

Here are some of the baths (and one kitchen) in Landmarked houses:

The bath below is not in a landmarked house

And now for comparison, a Usonian offered by the original owners:

and a Wright bath

Oh, I agree it's possible to renovate an architecturally significant house without necessarily restoring it as a time capsule--doing sympathetic, but clearly not original things. I don't think this is often the intent, and when it is the intent I often think it falls short anyway. But I am wondering at what point does any significance the house have essentially become meaningless because the original intent is so diluted.

The white modernist house was designed and lived in by Benjamin Gingold, who was a professor under Ralph Rapson, so it's at least Bauhausian in principle. It was influenced by a sabbatical in Mykonos and by Gaudi (the bath and stair rail mostly, I think)

"...not Wright!..."

Wish I'd said that! Yes, it's clearly possible to remodel the interiors and exteriors of a house with strong architectural character and to loose all of the original character which made the house a standout. Your photos clearly demonstrate that.

"Landmarked" house regulations vary from one local jurisdiction to another (when they have them at all). Some regulations apply only to the exteriors, while other regulations may be more stringent and have application to the interiors as well, although this is more rare in my experience.

Wright's approach to residential design was to put the space into the commonly used joint spaces, where the entire family might spend time together. Thus, kitchens and bedrooms were often small by comparison.

I think 3-6 car garages and humogeous mud rooms were rather rare in his work.

"Modern house by Mies is turned into a Cape Cod with Anderson tilt and wash vinyl windows covered by frilly curtains and crochet cushion covers"

Fingernails on a chalkboard.