I have been asking ancestry the same question for the last 10 years, but they just ignore me hoping I will go away.
I use the first name search all the time, because of al the miss transcribed entries for my family name.
It takes me days sometimes to find a family, what with age date changes, misspelt birthplaces, the list go's on.
What's even worse is that even if a record exists on or in the data base, it does not mean the search engine will find it, even it all your entries match the record exactly !!