International Style architecture, while maybe not aesthetically pleasing, isn't a bad style of architecture for street level retail. And actually, it's quite the opposite. Since the International Style typically produces boxy buildings, they can conform well to downtown blocks which are also square/rectangular. For me, the worst offenders in Austin are One Congress Plaza, 100 Congress, Hobby Building, 700 Lavaca, Lavaca Plaza and 816 Congress. But even so, those buildings could be retrofitted to add street level retail. It would be more difficult with One Congress Plaza, although, I could see street level retail being added to the east side of that block where the bank drive through is. Bank of America Center originally did not have street level retail, but now it does. They could add retail to those other buildings also, even if they had to do some structural changes to their street level facades.
I don't think this has been posted here before. I saw it posted at SkyscraperCity a while back.
And here's the other one that I think most of us have seen.