From a grass roots perspective - Man Utd are a british club and therefore their youth development focuses on developing British players (they can't sign foreign players until x age) - hence it's always nice to see a British player make it from academy to first team, do you not agree?
It's only when they get older that if there's a talent who is better than what we have and we can sign and bring in at 14/15/16 then it should be an option.
I don't really care about how many British we have in our starting XI given the last ten years, but I think every United fan would love to see a core of academy players in our starting XI though
England is no friend of Manchester United. As Sir Bobby said, the FA inflexibility led to the Munich crash while players like Beckham and Phil Nev were crucified for mistakes with England. Not to forget the media bias towards English players and how they react when a foreign player threatens a local player's first team place (ex Martinez vs Maguire or DDG vs Hendo). So we're better off not having any English players.
Having said that the academy is important even when its failing to produce WC players.
A- Squad players tend to cost the club money. If 4-5 youth players are able to play at this level then we can spare that money for the real stuff (ex bringing in WC players)
B- A good academy like ours tend to be self financed. That's because players who simply do not make the grade tend to be sold at lower divisions for profit
C- The homegrown rules need to be taken into account and local talent cost alot.
Nevertheless I do worry about our academy
A- It hasn't produced WC players for a long long time
B- The players it had produced have flaws in their character (Hendo, Lingard, Pogba etc) while some are utter jerks (Greenwood, Morrison)
When SAF took the job he led a proper clean sweep within the academy ranks. That lead to a drop of talent in the short term but would pave the way to the class of 92. I believe that ETH might need to do the same.