I get you minkyhead, I have previously always done the same. I tend to keep my bikes and pile miles on them, they do depreciate quickly so why not is my thinking
The 650 is only my second brand new bike in 40 plus years ( the first was a TSX125 when learning) so I treated myself to a warranty ( a novelty for me ), and I am lucky to have a dealer I trust (CJ Balls).
I was going to make this the last warranty keeping service ( though I change the oil mid way myself ) but the next one is a minor service so is not expensive and will mean I have another 15,000/ a years more warranty for a couple of hundred quid.And parts is half of that which I would have to get anyway after all.
As a side note the tech came and spoke to me when I picked the bike up to congratulate me on the condition of it and said it was " good to service...unlike some " ,he thought it was in for a 15,000 mile mayor / valve check service and was surprised when turning it on to see 30,000.
I thanked him but didn't have the heart to tell him it has only been washed once this year ( just before the service )........GT85/ACF 50 rocks , or that I service the brakes myself too, and know how to use grease/ copperslip
Ho Hum