Whatever happened to player endorsed/signature irons?

There was a time in golf equipment history when one could easily buy clubs with prominent player's names stamped on them, as "signature" irons. In the 40's and 50's Robert T. Jones, Gene Sarazen, Byron Nelson, Hogan, Patty Burg, Jackie Pung, (really the whole MacGregor autograph line).

Quick Googling reveals Lee Trevino, Arnold Palmer, Tony Jacklin, Tony Lema, Tom Watson, Tom Kite, all with their own brands of irons. (Nicklaus with muirfields as well).

Now I realize today we have Tommy Armour and Ben Hogan, but they are both quite dead and not exactly modern pro golfers. Neither was Byron Nelson on the early 90's clevelands. My question is when and why did this trend die out? Why do we not have "Callaway Phil Mickelson 'Lefty Limited irons'"? The closest we have are some Tiger logo stamped blades. Today's club naming conventions are basically picking a string of letters, numbers, and forged, mb, cb, and/or tour. What happened?

Good question! The trend seemed to petter out in the '80s and from then the focus seems to have been on brand endorsement. Perhaps the increased move towards custom fit is a factor? Lure you into the brand through big name endorsement and then have a whole range to fit you into rather than one specific set? One thing is sure, it will be a carefully considered commercial decision by the manufacturers!

I have these signature irons in one of my bags in my home office.

 "Today's club naming conventions are basically picking a string of letters, numbers, and forged, mb, cb, and/or tour. What happened?"

These guys don't demand a pay cheque.

I own a set of Daiwa DG273 irons. The original production were endorsed with "Designed by David Graham". My set don't have this endorsement. I bumped into David Graham a few years ago and I asked him why some sets do and some sets don't. His response, "Because they stopped paying me." I picked up that he was still a little bitter.

When I became aware of golf back in the late 60's, the only named clubs in green grass shops were Walter Hagen and Ben Hogan. The other name branded clubs were sporting goods-dept. store level.

I think I still see a sticker on the face of the 8 iron. You looking to sell?

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I think @OldTom is about right. Wasn't it unusual back in the Sixties and Seventies for pros to get paid by manufacturers to play their clubs? Maybe a very few top pros got paid, but not all, and not the amounts we hear of today?
Perhaps instead of being paid to play, players could make money by getting their name on a range of clubs?
Now, manufacturers sign players to represent the brand, rather than a specific line of clubs. For manufacturers, that's probably a good thing when new lines of irons are coming out every two years (and often faster than that). I suspect that putting the name of a player on the club weakens the impact of manufacturer's name as well. The manufacturers want their name to be remembered over the name of a particular player.
As for modern clubs, the only exceptions I can think of are the TW irons from Taylormade (which OP mentioned) and Callaway's PM grind wedges, which is not exactly the same as signature irons.

I think it's true that the top line clubs didn't have player names on them (in the US at least) but it was slightly different in the UK where player endorsement went on top and mid range clubs.

Just had a quick look at my own collection and was surprised by just how many names there are:

Fred Daly, Bobby Locke, Henry Cotton, Peter Thomson, Gary Player, Tony Jacklin, Ray Floyd, Jack Nicklaus, Peter Alliss, Eric Brown, Arnold Palmer, Max Faulkner, Roberto de Vicenzo, Seve Ballesteros and Johnny Miller.

I wonder if there was also a decline because the store-line clubs, which were the primary US player-endorsed clubs, became game improvement irons that no pro would plausibly play. Not that they would have played their name clubs back in the day, but at least back then they would have looked somewhat similar to each other.

It would be interesting to know the most recently made clubs with a player's name on them. I can think of Greg Norman in my playing time, maybe as late as 1996.

Players change irons every year so there's no point or market for it

Ha! After the way he choked in '96 I don't think anyone would want signatures on their iron heads anymore.

You are probably right. I was thinking of Nicklaus, but he left MacGregor in late 1992. His signature was on the JNP's. I was also thinking of Curtis Strange when his signature was on the sexy Maruman blades he was paid to play. They were both before '96. Norman had his signature on his forged irons, and I vividly remember the picture of him leaning down in the agony of defeat, and you can see in his hand the back of the clubhead clearly visible.

I bought my first set of clubs in 1959 , Spalding DonFairfield models. My next set in 67 we’re Spalding Bruce Devlin models. At the time player autographed clubs were sold through department stores and sporting goods stores . Only golf pro shops carried the pro line clubs. I think this all changed when a lawsuit by I think Edwin Watts won and since then golf shops are any place selling clubs can sell pro lines.

If the quiz what pro last had his name on a set, I'll go with John Daly. I don't have any to show. I do remember wanting a set of Wilson Andy Bean's.

I bought my first set of clubs in 1959 , Spalding DonFairfield models. My next set in 67 we’re Spalding Bruce Devlin models. At the time player autographed clubs were sold through department stores and sporting goods stores . Only golf pro shops carried the pro line clubs. I think this all changed when a lawsuit by I think Edwin Watts won and since then golf shops are any place selling clubs can sell pro lines.

Maybe because the pro's are expected to show up with the new version of a manufacturer's clubs, more so than the public could be expected to keep up with?