I hope everyone is following this "saverome" instagram account with almost daily coverage of Roman monuments:
https://www.instagram.com/p/BAFeYrRxQ8H/
This one points out that Trajan just put up a bare pole for his famous column! It's famous carving of Dacian conquest or whatever may have been designed at the time, but was actually implemented or paid for or at least installed later, such as by Hadrian. So it's not an expression of one leaders ego, but maybe more of Rome itself.
Was Hadrian unusually humble... remember he left a predecessor's name on his pantheon? Or maybe that had a slightly different story which I think was also covered in instagram. Anyway the facade of architecture may have a different author than the person famed for the initial build. I recall many renaissance buildings in Florence started without a facade, then it was added (or not) much later possibly in different tastes. I think British tourists actually funded the facade of the famous cathedral there for example,