Indeed. but then better players than him (which would have been great in this United side) like Di Maria, Hernandez and Evra left under LVG too, without getting properly replaced (in case of Evra, we replaced him with a great but inexperienced Shaw, but still think that 2 players for each position is ideal for a team like ours).
LVG made a mess in transfers and definitely Welbeck would have done a good job in this team. However, he is far from a top player (or a very good one) and could easily replaced. He isn't a player that I wish we would sign, and there are absolutely tons of better players than him.
If we want to ever become a top team, then Welbeck wasn't and isn't the answer. Obviously, if you remove an average player and then in his place play poor players, then things become worse but that talks more about LVG deluded mentality than for Welbeck's ability.