@pipelanus brings up a subject close to my heart. Since I’ve just poured a drink, please indulge me on this…
My father always had nice clubs. He Had a 3-PW set and then he had a few sand wedges, probably all 56 degrees. There should be a rule to limit loft at 56 or 58 degrees, but I digress…
Club manufacturers started to make stronger loft irons, so the 48 degree PW became a 46 degree. The universal standard SW was kid of always 56 degrees, so this “gap” of 10 degrees gave them an opportunity- “The Gap Wedge” was born.
Some companies, like Callaway, rebranded the whole set- it would go from 9 iron to 10 iron (PW) to A wedge (50-52 degrees) to SW (54-56) then Lob Wedge (58-60.) They did this not because anyone needed it, or was good enough to manage the full arsenal of wedges, but rather because the rules say you can carry 14 clubs and golf consumers will buy just about anything.
What happened next was also pretty crucial- Cleveland and Vokey wedges started to put the loft on the wedges and people’s synapses started going haywire. Suddenly, 22-handicaps were buying 52, 54, 56, 58, 60 combos rather than just getting good with one club (which they should have been doing in the first place.) The most maligned would actually bend a 58 to 57.
Like any good company, Cleveland, Vokey etc, had to grow sales. The natural move was to create new offerings. So instead of going up to 64, 66, 68 (that would come later) then went down in the bag to 46, 48 and 50. Why? Because the same sucker who “needs” a 54 instead of a 56 will buy your 46 degree if it means “more workability” from the rough.
The wedge world is gross. It’s literally corporations taking advantage of senior citizens on fixed incomes and nobody says shit about it.
So to answer your question, the reason people do it is mostly because they are suckers or have an ego that is likely costing them more than they will ever know.
Keep your PW.