This is, of course, a matter of opinion. I would argue that the veto is a valuable tool because of the fact that checks and balances are an important part of a democratic system.
It is important in a democracy that no person or governmental body should have too much power. Checks and balances help to prevent this from happening. The veto is an important check on the power of the Congress. If there were no provision for a veto, it would be much easier for a Congress to enact extreme legislation that was not in the public interest. Because the veto exists, Congress can be forced to be more moderate and measured in its actions.
A veto could be dangerous, but in the US system, it is not all-powerful. The President's veto can be overridden by Congress if it thinks the President has gone too far. Therefore, the veto is not a serious danger to democracy.
Checks and balances are important in a democratic government and the veto is an important check. For this reason, it is a valuable tool.