The sons of Lord Shiva, Ganesha and Muruga (Kartikeya) are very famous and worshipped by many, but not his only daughter, Ashokasundari.
What is the reason behind it?
It's probably because the story of Ashokasundari is only attested in the Padma Purana; you can read the story starting from page 1280 of this section of the Bhumi Kanda of the Padma Purana. (If you want to read the rest of the Padma Purana, see my answer here.)
And Ashokasundari is described in the Padma Purana as the wife of Nahusha and mother of Yayati, when other scriptures say that Nahusha's wife was Viraja, daughter of the Pitris (ghosts of departed ancestors). (I discuss Viraja in my question here.). Here is what the Harivamsa says, for instance:
The ancestors of Kardama Prajapati are the descendants of Pulaha Prajapati, and these are the fatherly gods collectively termed as Susvadhas ... [T]he brainchild of this group of manes is lady Viraja who is the mother of king Yayati and the wife of King Nahusha.
Here is another quote from the Harivamsa saying the same thing:
King Nahusha begot six sons through a damsel of fatherly gods, known as lady Viraja, or lady Suswadha, to wit, these six Indra-like sons are: Yati, Yayati, Samyati, Ayati, Bhava, and Suyati
The Vayu Purana has similar statements. So the story of Ashokasundari is thought by some to be a later interpolation to the Padma Purana.