The trend of using surnames as first names originated in the states and now has sadly moved over here. In my opinion the names I mentioned sound awful, americanised and chavvy.
The daft comes in when you consider that the names being used for little girls i.e. Madison, Emerson etc are MALE surnames (meaning SON of). That to me is very much daft.
Tierney is a good Irish surname. It is not in use in Ireland as a first name.
OP - Conlaodh is lovely. There is also the aglicised version of Conleth which is also nice and easier to pronounce!