I agree that bench options are very important. I think you're being very harsh describing Skipp as a "pretty poor" player to be honest, I agree he is raw, but he has facets of his game which Ange can work on and turn him into a very servicable 6. And besides, I don't think Skipp will see a lot of action once Bentancur is back fit, it seems logical that Bentancur and Bissouma will start in the 6/8 spots and Sarr will be our first pick off the bench, which, with 1 game a week for the large majority of this season, is actually very very good depth off the bench for the CM spots.
I agree we have poor depth off the bench in most of the rest of the squad, Royal and Perisic pretty solid and offer something different, but very noticeable downgrades when it comes to LB, CB, AM, RW.