Maybe there are a few of the more senior collectors here who went through this or at least know about it for sure. So this post might be teaching and getting educated as well.
I did a little digging, didn't take much, to find that in 1986, there was only the 1oz/$50 gold eagle. In 1987 the 1/2 oz was added, and in 1988 the other denominations were added.
So I had made a comment in my own collection thread that 1993 Philadelphia Set was the first set that I thought the gold eagle was in. Most collectors only think it the 1995 10th Anniversary set.
I know this isn't true now as they had a 2 coin set in 1987, as soon as there WERE 2 denominations, and the 4 coin was added in 1988, so these sets go way back.
So yes there was also a 1995 4 coin gold set, just sharing an image off the net.
The story goes that when you ordered your gold set from the mint, you just had to check a box to get the "bonus" silver eagle along with your gold set.
So the way I would understand it, if you didn't check the box, you'd just get the 4 coin set as pictured, if you DID check the box you got the 10th Anniversary set.
I would imagine collectors who'd been collecting the gold eagle sets from the start might not want a set that was different from the other sets? That's the only reason I could imagine that someone would not want the extra eagle.
My understanding also is that collectors who wanted the
ASE, and could afford to, would buy the set, sell the gold and that way would actually end up having the whole set paid for by the sale of the gold!
***EDIT*** I looked through the other posts that I mentioned. I had said the 1993 Philly Set was the first *special* set that the silver and gold eagles were in. I would stand by that comment. I'm not sure if a normal 2 or 4 coin proof set would be considered by most to be a special set. Up to individual interpretation.

