why would organisms break the bonds of organic compounds

Organic compounds decay at a wide variety of rates and by several mechanisms. Conditions that cause organic decay include temperature, exposure to air, light, water, and contact with metals, glass or neighboring organic compounds. An organic molecule is a large and complex molecule with atoms of carbon on it.

These organic molecules can occur naturally like in oil, plants and other living matter; or they can be obtained by synthetic means. Regardless of the path, at the end, the large molecules are obtained by adding a considerable amount of energy. This energy can be obtained naturally from the light of the sun or, again, by synthetic means. In both cases you count with a large and complex molecule that is useful to man.

This large and complex molecule is at very high energy levels, from a chemical point of view, and becomes an unstable and highly reactive molecule.

The lower the energy level, the more stable the molecule will be; this way the molecules would like to go back to the energy levels before the system was energized.

And like everything else in nature would try to decay if the could to reach equilibrium at lower levels of energy.