Before the 1820s there didn't exist much controversy over tariffs, and people like John Calhoun supported the tariffs. Why did their opposition...

High tariffs had met with some muted opposition early in the nation's history, both because they were seen as injurious to the export-oriented South and because their revenue could be used to finance government activities (like building canals and roads) that some saw as dangerous overreaches of federal power. But the rapid industrial growth of the North and the attendant growth of the cotton/slave economy in the South changed the political dynamic. Protective tariffs were good for Northern textile manufacturers, but not for Southern planters, and the increasingly higher tariffs in 1824 and 1828 were seen in almost conspiratorial terms. Southerners had also been alarmed by the resistance to slavery's expansion that emerged in the Missouri Crisis of 1820.

Many historians, most famously William Freehling, have also argued that tariffs were seen by South Carolinians as dangerous in the precedents they set. If the federal government could enact something Southerners saw as so blatantly hostile to their interests, then they might destroy the institutions (especially slavery) that undergirded Southern society. At the very least, the industrial North held the power to legislate against the South. Calhoun himself wrote that he considered the 

Tariff, but as the occasion, rather than the real cause of the present unhappy state of things. The truth can no longer be disguised that the peculiar domestic institutions [meaning slavery] of the Southern States...has placed them in regard to taxation and appropriation in opposite relation to the majority of the Union...

Some Southerners had become convinced since the Missouri Crisis that forces in Washington were aligned against them, and Calhoun's doctrine of nullification was seen as a means to resist these changes. The irony raised by the question is that Calhoun himself had been one of the country's most ardent nationalists. Indeed, this was how he positioned himself in his run for President in 1824. The best answer for why Calhoun abandoned this position to become the leading spokesman for states rights and slavery itself is to say that Calhoun, as a politician, understood which way the political winds were blowing in his native South Carolina. His was the position of the powerful planters in that state.