Why are some nickname type names more 'acceptable' than others?

[bluecars]

I have noticed on here that some nickname type names seem to be seen as not substantial enough to be 'proper' names - examples that spring to mind are Molly, Ellie, Millie etc. However, others which are also shortened versions of other names seem to perceived as ok - Katie, Sophie for instance.

Can anyone explain to me why this is? I genuinely am interested to know. I ask as I really like the name Cassie but don't want to give DD an 'insubstantial', nicknamey name and don't like the longer versions like Cassandra etc. Thanks.

Oh, you see badtime, I wouldn't inflict Dolores on anybody (not least because of its meaning!), but I have to admit I don't think of Lola as a real name. I actually had a great great aunt Dolores known as Lolita, though she predated the novel by about half a century...