I like your question (and I am very curious about it too), but I'm not sure if there can ever be a definitive answer. There doesn't appear to be enough information to say for sure. I find it equally interesting that, not only were they named, but the subsequent verse describes their beauty, and the inordinate value that Job placed upon them (elevating them uncharacteristically to level of their brothers).
Given the fact that their names all appear to reference their intrinsic beauty (cf. @user12422's answer), it seems to me that these verses are intended to convey the remarkable abundance of Job's restoration. God didn't just give Job 10 new children to replace the ones who died -- He gave him the three most beautiful daughters in the land. This coincides with the fact that God doubled Job's possessions from what he had previously; cf. Job 1:3. (Note that God doubled his possessions but not the size of his family, because, presumably, "7 sons" was already considered an ideal number, and "3 daughters" was a sign of completeness and divine approval; cf. Job, F. Anderson, p. 79.)
The prevailing idea seems to be that God didn't just restore Job to his previous condition, but blessed him abundantly beyond what he had experienced before his misfortune. In that sense, the names of the daughters might just be an expression of Job's delight in his new-found blessing (similar to the way that the names of Joseph's children symbolize the work of grace that took place in Joseph's heart; cf Genesis 41:51-52). In other words, these names are Job's personal testimony that warmth and perfume and fruit have once again filled his soul.
Not a definitive answer, mind you; just my own reverent meditations.