summarising the reasons why we have the haber process in the first place.
-extensive use of ammonia based products in society, e.g. TNTs, fertilisers, cleaning agents, etc...
-advent of WWI. germany's only supply of nitrate products come from chile. british naval blockade meant germany was starved of its supply of guamo. (i think thats how its spelt). had to find a way of getting nitrate products.
-developed the haber process to produce ammonia, forms the basis that can combine with other products to get nitrates. now, germany can feed its army better (with the help of fertilisers) and arm soldiers better with explosives (e.g. TNTs) and so prolonged WWI.
why did the process stay?
-germany wanted to become more independent (no need to rely upon chile for trading for nitrates)
-the haber process has become more efficient
-for its efficiency and productivity, it is a globally recognised process
-increase in demand for nitrates to develop more products (e.g. detergents, refrigerating agent, better fertiliser, as a food source for animals like fish, etc...)
-many people and businesses adopted the method, and so now it is widely used. ammonia is among the most produced chemicals in the world, including sulfuric acid, sodium hydroxide, etc...
hope this helps, M.D.