Even if that's true, that doesn't justify overpaying unless he delivered outsized results and/or made it possible for another player to deliver (e.g., demands double coverage so someone else had an easier time). Individual stats help in judging how good he is (and he's very good at catching in traffic and YAC), but team stats help judge his impact for the thing that matters the most: wins. Unless we run an offensive system built around a slot WR as the primary role, it's just not valuable enough to justify overpaying. Yes, I am aware of the irony in that last sentence as we clearly did run an offense with high utilization of our slot receiver, but it didn't get the results we all want: wins.
Let's say our field goal kicker was the best player on our team: Didn't miss a kick all season, was hitting 60 yarders so we won some games we shouldn't have, was able to rally the troops on the sidelines, etc. -- how much would you pay for that player? You might say something to the effect of "He's a really important piece of the team, so I'll pay him a little above market or give him some guaranteed money", but you wouldn't say "pay him whatever he wants" or "pay him like a QB".
I think it's pretty clear from the teams behavior around handling the contract negotiations and by not locking him up last year, that after seeing Landry up close for 4 years, they have set a price on his contributions. If I were to guess, he's fallen victim to "One ****up wipes out 99 good play's" -- we're (here on the boards) looking at receptions and the coaches are looking at routes, penalties, and contributions to and dedication in the WR room .