My Benchmade blade won't break like yours. My Benchmade holds its edge so well, it would probably cut your blade in half and I can still shave with it.
You get what you pay for...
The most obvious reason for spring assist is that they are legal in most areas. Spring assisted knives are not subject to the same regulations are switchblade knives. The are an excellent alternative to the automatic knives. You just give the blade a push via the thumb-stud (and many of the knives have flippers that you can press as well) and the knife takes over opening the blade the rest of the way IE: spring assist has no push button.
*** Don't Mess With TEXAS ***