i think the point is that if you decide not to run them in atall it is safe to say that nothing bad will happen, however i have two freiends who sell cars, one porches and the other BMW. When you buy a new 911 the engines are fully run in on a engine dyno, they do this to garantee that you will get atleast the power they claim for that model, hence it would make no difference to the engine from thrashing from day one. BMW also say all there cars are run in, and some people take it easy and others don't, however if you speak to the mechanics they reckon cars that are treated nicely for 1k feel stronger than one which has been thrashed. They employ a policy on running their demo cars in, regardless what bmw say.
you pay your money you make your choice, thrash or don't thrash, who cares really, if it blows up take it back. I have always run my cars in, regardless of what it is, i think they perform better for it in comparison to a spanked version.