You should at least recognize that poor Mr. Radcliffe was given an impossible task. There was no possible line that would not have “left large pockets of Muslim enclaves inside India and large pockets of Hindu-Sikh enclaves in Pakistan.”
The line you reference was drawn across British India, the provinces ruled directly by Britain. In theory, the princely states were allowed to decide which state they would join, or they could remain independent. In practice, geography determined which state they went into.
However, in the obvious case of Kashmir, a Hindu rajah declared for India despite about 75% of his population being Muslim. That’s pretty arbitrary and artificial.
And now you are parroting total liberal Anglo-American drivel. Except for just “the valley” Kashmir is predominantly Shiite Muslims as opposed to Pakistani establishment being overwhelmingly Sunni dominated. The Maharajah initially decided on staying independent but Pakistan army backed by Pathans tribals invaded and overran Kashmir. That's when the Maharaja fled to India for help, and India extracted an instrument of accession from him in return for expelling out the Pakistan army and the Pathans.
Between India and Pakistan, 90% Kashmiris would without doubt pick India. Most of them are well aware that Pakistan itself carried out a lot more ethnic genocide of Muslims (Bengalis, Shiites, Mohajirs and Baluchis) then India ever did.
” In theory, the princely states were allowed to decide which state they would join,”
That was only a British provision (a last ditch attempt to carve up India into as may parts as possible). In practise neither India nor Pakistan allowed any princely state to remain independent. There was no way they could have stayed independent.....too many land locked princely states, plus the people wanted to join India. Also their legal claims end with the end of British control.
Hyderabad had a Muslim Nawab with 90% of his subject being Hindus wanted to stay independent or join Pakistan (and his state was WAY down south). Same with Junagadh (Muslim Nawab and Hindu majority) but right near India-Pakistan border. The Maharajas of Jaipur, Jodhpur, Udaipur, Patiala are all near the India-Pak border.
Over several decades, Hindus (Kashmiri Pandits) were forced to flee the valley by Pakistan backed terrorist and so today you have an artificial majority of Muslims in Kashmir, just as you have in rest of Pakistan.