The influential Dutch architect Herman Hertzberger, who at age 90 is a professor emeritus of his alma mater, UT Delft, is a designer whose "flaw" I can respect. He was an early proponent of Structuralism, which in a nutshell says "Hey don't forget that actual human beings have to live and interact inside these places we design," and the knock on Hertzberger has been that he's less concerned with how something looks and more concerned with how something works for the people who use it.
"Oh well, in the end it wasn't really very nice from the outside, was it? A beautiful exterior was also not my first task as an architect. It could have been a bit cozier, but I have always had the music experience as a starting point – unlike a lot of other architects who would go for a beautiful exterior. When people have experienced beautiful things indoors, they no longer see the relative ugliness outside. The outside is therefore not the most important thing for me. I have been accused of that."
"The floor in the hall of the kindergarten section has a square depression in the middle which is filled with loose wood blocks. They can be taken out and placed around the square to form a self-contained seating arrangement. The blocks are constructed as low stools, which can easily be moved by the chidlren all around the hall, or they can be piled up to form a tower. The children also use them to make trains. [...] [The] square hollow gives a feeling of seclusion, a retreat, and evokes associations with descending into a valley or hollow."