Whose fault is it then if a lawyer impedes progress on an important deal? In my opinion, the fault lies with the business side. Lawyers provide a service - just like consultants. You wouldn't let a consultant run your business, so what's up with placing all the blaim on lawyers if deals get stuck? It's the business side's fault for not properly managing their lawyer and not telling him what exactly he is there for.
Legal education makes you an expert in spotting problems and helping put consensual agreements between people in enforceable language. It doesn't make you nit-picky per se, it's more a matter of character. There are first-hand lawyers out there who are probably even better at the business side than the business people themselves (think Peter Thiel) - they have an expert ability to spot lots of problems, and then proritize those and decide what's important and what not. Full disclosure: I am a Ph.D. student in law and that's what my education provided me with - an ability to prioritize problem-solving according to importance.