I wouldn't say it's incredibly poor value.
Paying in full 599£+118£ for apple care. Looking on websites that buy used phones loss in value is approx 43% (257£ in this case), and this price is similar to ebay. So it would cost you 257+118=375£ to use it for a year
For upgrade programme you pay 11 x 33.45£ + 49£=417£
Sure you can add couple of pounds for better resell deals but the difference would be worth in my opinion for easy upgrade to the latest model.
If you don't plan to buy extra insurance anyway than it's obvious it doesn't have value for you because you're paying for something you don't want
and if you buy apple care and sell the phone next year it's a loss as you paid in full.
iphone 6s 64GB 619£ (price at release) 351£ now best offer on sellmymobile (this is where I took 43% from as a loss in value).