I wonder if -Stef-'s name influenced LastFootnote's interest in the card.
It's impossible for me to give a 100% objective answer to this, but I doubt it. In my experience, skill at playing Dominion does not directly correlate to making good Dominion cards. I'm not in love with most of WanderingWinder's cards, for instance (Nothing personal, WW).
The reason I like it so much is that it's got a very unique, yet elegant and compelling mechanic.
It certainly makes me give the strategic implications a second thought. I'm not seeing it, but maybe it is obvious to -Stef-.
I wouldn't read too much into it. According to -Stef-, this is his first fan card. I messaged him back, asking if he wanted to at least add +1 Action to it. He said had considered both that and allowing you to gain another Silver onto the mat when played (instead of swapping). He was afraid that those would make the card too powerful. That's a common mistake among new fan card developers: erring on the side of cards that are too weak. I've certainly done my share of that.
EDIT: I thought the same thing, by the way: that there might be something I was missing about the card. That's why I contacted -Stef- about it. It's possible that there's something we're both missing.