What are the problems or dangers of placing elastic power in the hands of a representative body?

I understand that this refers to Article I, Section 8, where the government is given all the power that it needs to fulfill its duties.

The danger here is that the specific powers that the government should have are open to interpretation and that this enables, if unchecked, an abuse of power on the side of the government. So: additional measures are necessary to ensure that this abuse does not take place.