A sports science degree is useful,as is any degree, but not essential to help with your coaching.
In my neck of the woods there are TOO many people with sports science degrees and they are devalued a bit because of the lack of employment opportunities.
The science part of it sounds great as it can be applied in a number of roles within sport but the best way to become a good coach is by coaching,surprisingly enough.
Can i ask what degree you are going to do?
Thats very narrow minded and ignorant opinion.
The best coaches in many sports have sport sciences degrees or at least in depth sport science knowledge and they directly attribute the quality of the coaching they can provide to the knowledge they have.
Take Mourinho, his entire coaching blueprint is based purely on the ENTIRE final year of sport science degree combined with knowledge he obtained from learning from other coaches. Without that final year plan Mourinho would not be Mourinho.
As for your point about jobs then many coaches with sport science degrees do want to coach funny that don't you think?
I can understand your prejudice against coaches qualified with better methods than most can access. I dont mean knowledge either, I mean from contacts and doors opening up that would not be accessed by most.
I find having a sport science degree has directly impacted the quality of my coaching, it allows me to me win more often and better.