The former England defender replaces Stuart Pearce, who left the role in June following a disappointing European Championship campaign.
Southgate, who was previously the FA's head of elite development, will also oversee the coaches with responsibility for the under-16s through to the under-20s.
Dickinson admits Southgate has great knowledge of the game, which he often demonstrates as a pundit on ITV, but says the FA's insistence on appointing an Englishman could have left them with a man who does not have the requisite coaching experience for the role.
"I don't think anyone can revolutionise English football," he told Sunday Supplement. "I think that is shooting for the stars and I think we gave up on that a while ago.
"We have all spent a lot of time with Gareth. He is on the road a lot doing his punditry. He spent 18 months at the FA looking at youth development. He knows his stuff and cares about his stuff. My worry is that it is a coaching job.
"It is a big coaching job. It is not just the under-21s but all the development teams and the one thing that Gareth's CV does not screaming is coaching experience.
"He had three years at Middlesbrough where he was thrown in at the deep end; he didn't even have his badges at that stage. He has now gone and done his badges.
"But I just think that if you are looking at wanting a guy who has the coaching acumen and experience, hopefully some new, fresh and radical ideas, you don't give it to someone who is a relative novice in coaching.
"That is my big worry. But the trouble is that when the FA say this is going to be an English appointment, which they clearly felt it had to be, then you are very much restricting the field."