Why did the British raise taxes in the American colonies? How did colonists react?

The British felt that the Americans should pay for the war as the British felt that the war had been fought for the benefit of the colonies.

The American felt that they had not benefited greatly from the French and Indian Wars. The crown had taken control of Southern Canada. The American Colonies were not allowed to take land in Canada.
The prohibition of 1768 prevented the Colonist from continuing their move westward. Virginia had claimed the Ohio River valley and land around what is now Pittsburg. Daniel Boone had established a fort in Kentucky and defended it at great cost. These lands were now "off limits" to the colonies.

Instead of gaining land as a result of the French and Indian Wars the American colonies had lost land. The Colonies were not happy about paying England's cost for a war that had not benefited the colonies as much as it had benefited England.

Also the colonies had fought along side the British in the French and Indian Wars. The Colonies had spent men and resources to help the British win control of Canada. So the American felt that they had already paid their share of the cost of the French and Indian Wars.

The British felt justified in raising the taxes the American Colonists paid. The American Colonists were bitter and angry at what they felt were totally unjustified taxes.