I think people grossly underestimate these coins.
I've looked for nice examples of these straight along and some of them are virtually impossible in true Gem condition. For instance I've looked at many many rolls and a couple thousand 1984 mint sets for a nice '84-P. A couple years back I found my very first true Gem. When I use the term I mean a well struck coin by good dies that is still virtually pristine. Most of these even in the mint sets were struck by bad dies, were poorly struck, and then they were damaged. The specific problem for this date is that the surfaces look awful because they are bumpy and wavy. They often suffer plating and tarnish issues. I'd grade my example only MS-65 because it has a couple tiny carbon spots (that will destroy it in time).
Bad Thad has it about right but collectors will find (as he knows) that some of these are very elusive. The reverse often doesn't strike up well and corrosion and plating is a problem with a lot of the coins.
I believe even a nice "gemmy" set (MS-63+) and better of the memorials is pretty challenging because of tough issues like the '84's and '79-D. I think that if collectors paid more attention to these they'd find there are some real challenges.
I'd love to have a roll set of these. I've just set aside the really nice issues which means I've got a lot of '88-D but not so many '68-P. Some of these dates just come spectacular Gem. The '88-D Is often seen as a perfect PL but others like the '79-D are usually awful.
Time don't fly, it bounds and leaps.