Idiom for something that is well designed but not commercially viable?

Is there a word for something that has been well-designed, looks good but can't sell. This can be an object or an idea..

Concept

As in Concept Car or "This energy neutral house was built from natural materials as a concept."

Companies often build such "concept products" as a marketing excercise and many are very well engineered, though not economically viable and the company has no intention of selling it, at least not in the immediate future.

If they built it with the intention of selling it and it didn't sell it would by definition be poorly designed and would be a White Elephant.

EDIT:

Thanks to Hotlicks for comments. There are some products (such as the Betamax) that whether due to bad luck or poor management, suffer because the market standardizes on the competitor's format. I would like to suggest the term victim of standardization for that.

I'm not sure if it needs padding out as a simile or can be used just as 'It's a Betamax'.

From Wikipedia:

Betamax

Developed by Sony Home movies, Home video Betamax (also called Beta, and referred to as such in the logo) is a consumer-level analog videocassette magnetic tape recording format developed by Sony, released in Japan on May 10, 1975....

The format is virtually obsolete, having lost the videotape format war though an updated variant of the format, Betacam, is still used by the television industry....

LThe SL-8200 was to compete against the VHS VCRs that had 2 or 4 hours of recording time.

Betamax and VHS competed in a fierce format war, which saw VHS come out on top in most markets....

The VHS format's defeat of the Betamax format became a classic marketing case study.

Internet examples:

Diller on Aereo: It's like Betamax.

Is SPB the Betamax of Layer 2? | The Networking Nerd

Commonly used in the entertainment industry is "Turkey" - And I think, although this is not supported in that Dictionary link, that its use can be extended to other things:

"You remember that thing we made? Brilliantly designed but turned into a bit of a turkey in the end"

Another related term is "White elephant" - Again this dictionary definition does not tally exactly with my understanding of the term to mean "useless and impossible to get rid of"

"They spent a lot of time on the design but in the end it was a bit of a white elephant"

I love Edwin's 'Betamax' reference, but I believe a better term would be critic's darling. It's widely used in the artistic fields and sometimes in technology to describe a thing that dazzles the press and the cognoscenti but fails to find a broader market/audience. (Cf. Segway, Jim Jarmusch films....)