I agree, everything you just said is true. They have used the TE position well and often in the past. He is a very good prospect that can block, get open and catch fairly well. And having a quality TE is very important IMO.
But, Big Mike is now calling the plays and he has never used the TE like that. I think he would rather draft another WR weapon to run a west coast spread offense, conjoined with a dominate running game. And they love Ferguson and they like Hendershot too. Ferguson is a do it all well TE. He reminds me of Witten when I watch him. Nothing flashy but makes plays and is reliable at all times. Hendershot is capable of breaking a big play and he's just nasty! He will drive DB's and LB's nuts. IMO, adding a top draft pick will be a major progress blocker to those guys. Also factor in that they intend to run the ball more and I just don't see TE being a huge need. Would it be nice to be super stacked at the position, sure it would. But not at the expense of filling the holes they do actually have, many of which are right where we need to be stronger to do what Big Mike wants to do.
I could be dead wrong; and don't misunderstand, I think a player like Mayer would be great to have on the team; but I just don't see it.