Breaking it down further, with WR, open is open. Elite quickness and speed with decent route running will give you windows where you don't need elite route running and hands. Plus you can gain more ypa on simple slants and such.
And as for drops, a slant that goes 80 will more than make up for the occasional extra drop.
Whereas QB, a big arm and legs will get you out of lots of trouble but inability to read the field can be a big liability against elite defenses. There is an asymmetry there positionally speaking
And then to your point...how well it all fits together is the greatest force multiplier on the individual draft decisions. Elite accuracy, quick first read, surrounded by a track team, ample use of misdirection....man cannot wait for the season to start!