Well it's just personal taste, and for me about my interest in name etymology and naming conventions. I don't particularly like the argument 'can you imagine a high court judge called XYZ?' that is simple snobbery.
I accept a lot of names that have derived from diminutives but feel substantial in their own right and carry the meaning of the original plus the history of becoming derived over time and having notable people associated- Janet, Natasha, Eliza and Margot in fact.
However, for me personally, most of the popular -ie names such as Hattie generally just don't sound substantive or whole to me, or clearly carry the meaning and history of the original name. They just sound diminished, smaller and sillier. That is just my opinion. I don't believe in nominative determinism and am sure there are hugely accomplished Alfies and Teddies out there but generally prefer the full name, nickname if wished option.
Harriet is simply more beautiful and interesting to me than Hattie. Same for Henry, Edward, Frederick, Dorothy etc.
For some reason the exception is Stevie for a girl. Not sure why!! I'm not a particular fan of Ms Nicks.