Why do you think the exine should be hard? What is the function of germ pore? 

i think exine should b hard enough to face the climatic conditions and hazardous envirionment.

n bout germ pore..

a pore in the outer wall of a spore or pollen grain through which the germ tube or pollen tube makes its exit on germination.

 I think that , Pollen grains have a hard coat becoz that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the female cone of coniferous plants.

 i thnk dat the exine should be hard to overcome the unfavourable conditions...nd thus exine is made up of sporopollenin which is the hardest and most resistant organic material...and the germ pore is present for the dehiscence of pollen grains when favourable conditions arrive..

Exine has sporopollenin that makes the pollen grain resistant to the climatic regions.

The germ pore it is the portion where sporopollenin is absent, it helps in the pollen tube growth.