I agree with you, that it should not be used be doctors as an excuse for not trying to improve their patients control.
However, as most things, this has two sides: I tend to get very frustrated when things aren't going my way and I feel I don't have control over every single detail - as it happens often with D. I'm well trained, but my body just isn't a machine. Having my D described as brittle helps me to relax and to say: "Well, my body is just very sensitive and it's impossible for me to control everything". It gives me a little more peace of mind and therefore mental health.
And in Germany it also helps you to get your insulin pump payed by your insurance company.