Revered 'Sant Tulsidas' has an explanation,
Rama was an avatar on a divine mission.
He came to oust the earth, of the burden of evil,
Had he not exiled, the demons, who would kill?
His sojourn in the forest was required,
An entire sequence of events later followed.
Would Kaikeyi, who loved Rama so dearly,
Could’ve forced her free will, the hardship of exile?