If you want to sell your product/look for investors you need analytics. The easiest way is to just slap Google snippet in there. If you decide not to do it you're off to self hosted analytics solutions which are just not comparable to google. Building small sites, blogs, informational sites is pretty easy without 3rd party scripts but when you're going into mid size ecommerce (by mid size I mean company that have decent advertisement and sales research budget) it's getting way harder to stay away from 3rd party analytic and marketing tools.