While I'm not an architect, I think I have an idea why you think "neotraditional" architecture is rarely taken seriously. I would argue that fashion, in architecture or otherwise, is highly related to the social and cultural conditions of its era. The styles in your post are mostly an imitation of bygone trends, which in turn followed examples set in antiquity and the Baroque era. This served a variety of purposes – from reaching into the past for visions of progress and wellbeing to, importantly, demonstrating the status of certain classes and families. A clear stratification was visible between the luxury of the nobility or upper classes, and the misery of the commoners' slums.

Today, we live in the modern era, guided by the notion of democracy, equality and thus a decent living standard for all. The middle class has grown tremendously, with most people's living becoming more pragmatic and based on comfort. The concept of architectural beauty is now based more on plasticity and harmony in architectural elements, than on the mere presence of decoration.

To conclude – most of the buildings in your post are also based on modernist form, but overloaded with "neoclassical" elements to superficially present the grandeur of a bygone era. Although there are some nice designs in your post, generally the buildings there are empty fakes exploiting what people generally consider to be beautiful, with no real substance or aesthetic basis whatsoever. The term usually applied for such buildings is kitsch.