Hoarding is simply the same as saving. Savings are what makes capitalism a viable economic model. Inflation is a stealth tax from those who have last use of new money (the poor, middle class) to the pockets of those who have first use of new money (the banks, wealthy, government).
It is not quite so simple. Standard economists worry that if inflation becomes too low (or if there is deflation), incentive to hoard increases and incentive to invest drops, which could lead to negative growth, the bête noire of capitalism.