Bottom line is the way it fell apart with Shanahan probably made it tough for them to get any serious consideration from the big named guys out there, and Dan Snyder's reputation goes farther back than that as far as not seeing eye to eye with his coaches. Jay like his brother is completely enamored by the QB position, and the Redskins aren't doing anything till RG3 is fixed. They have solid pieces on offense, could probably use another WR and patch up the OL. Defense needs a complete overhaul or somebody that can get them to play better, idk if Morris is that guy though.
They are keeping Haslett so far as I know. As far as big names go, I didn't want Jon Gruden or Cowher. My preferences were Roman or Bevell, would have settled for McDermott too. I wanted to stay away from that big name.
As for the areas you've pointed out, here is my perception.
For receiver, Garcon is a great #1 for us, and we have depth, but no true #2. That is definitely something that we need to address, and I'd prefer that to be a receiver with size.
The offensive line is actually pretty good for the most part. Polumbus at RT fell apart, so I hope we can find a RT in free agency, but I'm very happy with the offensive line. If RGIII can make better decisions to throw the ball away instead of holding it too long, we see the pass protection improve immensely.
Defense does need some work in the secondary for sure. We need a #1 corner, and Hall needs to go. Meriweather is a solid safety, but plays recklessly and I'd rather go for a safer option in the off-season. The other safety spot needs to be addressed as well. I really like our line. Orakpo may want too much money, Fletcher is gone, so we need to replace two linebackers.
Plenty of holes to fix, and it's not happening all in one off-season. One thing Shanahan and Allen did was draft pretty well, and we have some good depth, better than we've had under any other team in the Snyder era.