a few reasons spring to mind,
1) should the engine have an uncontained failure, parts should not enter the wing fuel tank area of the wing making a bad situation worse.
2) should the engine decide that it no longer wishs to go round and seizes and due to the torque of the engine it should rip its self off the wing the fuse pins should fail in such a manner that as it departs from the wing it should do so in a manner that due to its forward position will not excessivlly damage the wing and wing fuel tanks.