I have stopped listening to what Harrison has to say some time ago. Half of it is sadly the same gibberish drivel that also comes out of Dungy's mouth. And unfortunately this is part of this.
On paper of course it makes sense to have a player in your system that can stretch the field. But a) usually you have to invest a reasonably high draft pick or a lot of cap space to get a player like that and b) the surrounding pieces have to fit. But we are simply not in a situation where we can or should do that and people that want that deep WR threat are often trivializing the entire situation (i.e. "get a deep threat and suddenly the opponents will stop crowding the box").
There is no point in rebuilding half the team to change our identity so we can sustain a legitimate deep passing game. Especially because we would transition into a play style that is definitely not Brady's strength and more importantly might harm his longevity. And just to prevent the "Brady has a better deep ball than people give him credit for, see 2007" discussion; I am not saying he is a bad deep thrower but simply stating that the short passing game uses more of his strengths.
Realistically, the only thing we can really do is get 1-2 day 3 WR projects that fit the bill (and maybe some more UDFAs) and hope to luck out in finding someone that can fight for the ball 2-3 times a game. Because, again, there is no way that BB and McD will suddenly go away from our short passing game offense that has carried us to 5 straight AFCCGs.