Findings
I got a hold of our analytics and learned that new players creating an ID for the first time tried on average 7 unavailable IDs before successfully choosing (or settling for) one. Not only would players relive that challenge while changing IDs, they would further reduce the pool.

Though we had some serious conversations about how to revamp the system (teaser: Why do IDs need to be unique anyway?), that's a spinoff story.
So, funnily enough, with the business standing to profit from repeat changes, I spent a good amount of design time thinking about how to subtly discourage frequent changes.
Analysis
If you revisit the original reason for change--embarrassment--you might think "let's resolve this quickly." But breaking down why embarrassment happens, you see that you can only be embarrassed by something that you value.
In this case, when players are saying "we want to change IDs", what they are really saying is "we value how we are perceived by others on PlayStation, therefore we want our IDs to represent our current selves."
Theoretically, users should not be frivolously changing something that they value. No matter how cringey your first ID (or email address or screenname) was, it represented an important part of your life, and you have memories attached to that name.
Recommendation
In the midst of all the excitement players would feel with the long-awaited ability to change and the ensuing mad dash for available IDs, I saw the opportunity to remind them of how much they valued their time with PlayStation.
I recommended this line on the main ID change page:
"You've been playing as pottergirl14 since 10/12/2013."
I wanted players to see their name on screen (one last time) next to their account age, and used the language "playing as" to suggest social context.
My hypothesis was: if users spend time reflecting on the good times they had (and the bad) with their old ID, they would slow down and choose a new one wisely.
Results
Although there is no good way to measure the true effects of this design choice on ID selection, I kept a collection of anecdotes. Here are a few of my favorites:




After reading those, imagine for a second that we had chosen to encourage change. Perhaps said "Time for a change!" or tossed up something self-congratulatory like "It's finally here!".
We could have made it "quick and easy" to change, or thrown a "Are you sure? This change is irreversible" warning after selection.
.
.
.
Change isn't that easy.
I don't regret for one minute convincing a few people to keep their old IDs, even if it came about because we have a limited pool.
BONUS
Though we would have liked to open up the ID space more, it was not feasible at the time. However, we did also spin off a separate project to improve ID recommendations. The generated recommendations inspired articles such as "
The Best (And Stupidest) Recommended PSN Names We Could Find," but after 7 failed attempts, who wouldn't get a laugh out of balding-hades278?
The boring reason why we went with this ridiculousness: Humans have a much larger passive vocabulary than active vocabulary.
Recognition is better than recall. The recommendation engine's main job is to spit out words you forgot about until you find some inspiration.