Over the years of housebuying we've always had homebuyer's reports or a couple of basic valuations and one full structural survey. Only once did we ever not buy a house because of the survey and in that case, someone else bought it a couple of weeks later. It was supposed to have roof issues. I drive by every now and then and the original roof is still there and still looks fine and the house has been sold a couple of times since.
I guess we have surveys for peace of mind (leaving aside the mortgage requirement) but given that only a full structural survey carries any real liabilty for the surveyor - what's the point?
Surely, if you're happy with what you can see and as long as you can get buildings insurance on the property, you may as well not bother with a survey as you won't be able to sue them anyway, even if the front wall falls down 2 years after you bought it.
Have you ever bought without a survey and what happened?