There is literally no one arguing that he's the best WR in the draft. No one thinks he's a better prospect than Cooper. He also wasn't the best player available, not on any of the player rankings I saw. Maybe you have insight to the Bears board, but I doubt anyone knows that.
I don't care who he compares to as a WR, we didn't need a WR with the 7th overall pick. All of the top tier pass rushers, OLB's and safeties are now going to be gone by our second pick. We missed our opportunity to get a difference maker at a MASSIVE area of need in order to get a guy that grades out no higher than a #2 WR for our team. I just don't see how that makes us better. Teams aren't built with "athletic freeks who are the BPA" like you said. Good teams pick up difference makers in the first round and understand the value of a pick. Do you honestly think Belichek would have picked White #7 overall? I don't... And it would be a better fit for them than the Bears.
From NFL.com -
"Chicago Bears
Biggest needs: Receiver, outside linebacker, safety.
The Bears could get back to their defense-centric ways under John Fox. The wily head coach traditionally uses his initial picks on blue-chip pass rushers when he takes over a franchise (see: Julius Peppers, who went second overall to the Panthers in 2002, and Von Miller, who went second overall to the Broncos in 2011), and the Bears are in desperate need of a 3-4 edge presence, with new coordinator Vic Fangio heading up the defense. An electric defender like Clemson's Vic Beasley or Missouri's Shane Ray would certainly fit the bill as a rush OLB. The Bears have failed to sufficiently fill their safety need over the past decade, despite expending a number of draft picks on potential candidates. Alabama's Landon Collins is the cream of the current crop; an underrated playmaker like Arizona State's Damarious Randall could be an option on Day 2. If the Bears elect to replace traded-away veteran Brandon Marshall with a blue-chip pass catcher, Alabama's Amari Cooper and West Virginia's Kevin White are the likely candidates. Chicago could look for a value pass catcher on Day 2, which would make USC's Nelson Agholor or ECU's Justin Hardy potential fits."
White was no stretch at that position and plenty of people saw that as an option for the Bears. He was also the highest rated available per NFL.com and the drop off they project at WR is huge after the top two. Bears may have seen the buzz and felt there would be a run on WRs to boot. Maybe they put more stock in the offseason moves than you and I. Maybe Beasley did not interview with them well. Maybe they really hoped Williams would drop. Maybe they just took a best available mentality with the first pick. Either way, it is far from a bed crapping moment and I am excited to see him in a Bears uni.