The holes are staggered to give a better friction fit. ... Hard to say the long-term reliability, but probably good enough for prototyping.
I noted the staggering, but pushed down more, the pins will line up less on the board above. I'd guess cheap and reliable can't be attained at this price. If they included a 2-cent, 40-hole plastic piece (used to make headers) hobbyists could slide it on over the Joey to sort of re-align the header pins?
Ah, the Joey. Had to stop selling it and get rid of the stock, after receiving a "cease and desist" from a company that had registered the name "Joey". Also abandoned the "Joey Zero" I was about to release, that had a proper connector instead of the staggered sliding one.
Anyway - it took a few revisions to get the staggering right. Slow process because I had to get each interaction manufactured (couldn't test by drilling them myself, because fractions of a mm were important). Had to balance making a good connection vs ease of fit and, as pointed out above, how much it splayed the Pi's pins, making it harder to fit another board on top (which was the whole point of the Joey being a "sidecar").
In terms of long term reliability, yes, the issue is that the hole plating will eventually wear through after repeated removal/replacement of the board. The idea was that it would remain attached to the Pi most of the time, while the user swapped their various hats - it only interfered with I
2C and the address was settable via jumpers, so could coexist with almost anything.
History now of course, just wanted to comment because I hadn't seen this post from years back!