There's no reason to not buy a Stern if you're knowing what you're getting going into things. As far as the unforeseen disaster situations (ghosting, peeling decals, etc.), Stern has generally made those right by the customer.
I personally won't deal with the NIB headaches from Stern anymore, but if someone does their research and are willing to deal with possible hassles, then they should go ahead and order. Stern makes great pinball machines, that's undeniable.
What gets me is that people are willing to spend $5,000-$9,000 on a machine without educating themselves on the risks and common issues. If you're taken by surprise by a common issue with a problem on something that expensive, that's on you to some degree. Educate yourself first, and if you still feel good about it, pull the trigger. If you have doubts, wait on things or scour the secondhand market for a more proven product.