I see it much more like a domino effect. For instance, if we were to pick in this order R1-4 lets say, WR-ILB-CB-OG, and instead took a QB early, then each of the talent levels of those ILB, TE, and CB drop down one draft round, which is a considerable drop in quality of player. You are not just getting slightly less of player in "R2", you are getting less of a player in 2, 3, and 4.
Rd 1 Pk 13 - Corey Davis (WR) Western Michigan
Rd 2 Pk 45 - Zach Cunningham (ILB) Vanderbilt
Rd 3 Pk 77 - Jourdan Lewis (CB) Michigan
Rd 4 Pk 119 - Nico Siragusa (G) San Diego State
vs
Rd 1 Pk 13 - Deshaun Watson (QB) Clemson
Rd 2 Pk 45 - Cooper Kupp (WR) E Washington
Rd 3 Pk 77 - Kendell Beckwith (ILB) LSU
Rd 4 Pk 119 - Damontae Kazee (CB) SDST
Comparing model 1 to 2 above: you would be totally losing a very good OG and weakening by a whole draft round your WR, ILB, and CB, which could mean the difference in a good starter and a backup.
Now, what you are saying is more like this:
Rd 1 Pk 13 - Corey Davis (WR) Western Michigan
Rd 2 Pk 45 - Zach Cunningham (ILB) Vanderbilt
Rd 3 Pk 77 - Jourdan Lewis (CB) Michigan
Rd 4 Pk 119 - Nico Siragusa (G) San Diego State
vs
Rd 1 Pk 13 - Deshaun Watson (QB) Clemson
Rd 2 Pk 45 - Zach Cunningham (ILB) Vanderbilt
Rd 3 Pk 77 - Jourdan Lewis (CB) Michigan
Rd 4 Pk 119 - Nico Siragusa (G) San Diego State
I get it that in your thinking, you would simply lose the WR1 and everything else would stay the same. But still can you imagine not having Larry Fitzgerald on our team all these years. I suppose you could if in place of him you had gotten a possible Eli Manning, Andy Dalton, or hopefully more like a Phillip Rivers.
Its a gamble, but it is one all teams have to make eventually in search of that pot of gold we call a franchise qb. Maybe it's our turn again (ie. Matt Leinart).