I have to agree with Curious:  Tolkien, in his effort to create a Christianized epic (ala Beowulf), has reinforced the Christianized representation of various folk-type characters.

The "hag" or crone is made ugly, evil, and non-communicative, and often vindictive--thus she "loses" her agency and power and wisdom perhaps because the idea of a wise, experienced woman who can lead/advise is a no-no in early Christian society.  She is usually countered by a maiden, yet the maiden is not as powerful, and as Kimi notes, she's often required to take on a lover (which is the only way she gets agency).  Tolkien does have strong women, yet they are all "maids" rather than "crones" or "hags," which is in line with the acceptable Christianized viewpoint.

However, in many mythologies, the hag is celebrated as a model of/for empowerment. 

Hecate/Hekate is an example of a crone who has been viewed as both evil and as the font of wisdom:  Sappho writes of her as "Aphrodite's handmaiden," and in other poems she's described (again, by a woman) as "Mistress ruler of all mankind."  Yet in Macbeth, she's little more than a dark witch who sings around a cauldrin. Other stories have her wandering graveyards and haunting churchyards. 

Another such hag is Cailleach, a scotish sorceress with "teeth of a bear and wild boar's tusks."  Yet early stories actually have her creating the earth.

Witches are a more familiar example of the crone/wise women who has been re-defined as evil by a patriarchial Christian society.  In many stories, what we have translated as "witch" was originally was originally written as "goddess" or merely "old woman".  The original references have been harnessed/devalued, and what was once imbued with power and wisdom has been rendered evil and/or impotent by re-nameing them.

So instead of being seen as healer, empowerer, giver of wisdom, creator, and spiritual leader, she is depicted as useless, ugly, evil, and hidden.

Not all those who wander are lost.