[douche]

You apparently have not encountered the "architecture astronaut" archetype[1]. Your final sentence stands; usually they can't.

[1] http://www.joelonsoftware.com/articles/fog0000000018.html

[vonmoltke]

The issue with "architecture astronauts" is that most problems in software just aren't complex enough to warrant formal design. The core failing of these people is that they impose unnecessary design complexity in order to force the design to be complex enough to warrant formal design.

If the problem is inherently complex enough, particularly if it is multidisciplined, than it is the correct approach.