That's interesting to me, because "replayability" has always been one of the core considerations in game design, but with a Legacy product, locked-in choices and permanent consequences are one of the selling points.
I feel like those are on opposing ends of a spectrum: one the one end you have games like chess, go or even Magic the Gathering that are infinitely replayable but have little to no story.
On the other end you have story driven games (Gloomhaven or even Descent) that can be played only once because the second time through does not offer too much new content.
Somewhat tangential to that are roleplaying and wargame campaigns where new "content" is introduced constantly by the GM or, even better, as a consequence of player interactions.
I feel like there is still some niche for some kind of game that randomly/procedurally generates new content (maps, stats, scenarios) each week that players then print out and use for a session.
[/rambling ... it's time for the weekend]
You put "replayability" in contrast to "legacy" but honestly we played that game more times (15) than a lot of traditional board games.
You hit the nail on the head. The unfortunate truth is the vast majority of board games get played <5 times, often no more than once or even zero times! There's a long tail of games that get played way more than 5 times but the median has got to be down there. So the legacy games are less radical than they appear. If they're replacing one of those games in the very large bucket of quickly dropped games then they have no downside in terms of loss of replayability. And as you said, they incentivize replayability for my groups at least by essentially forcing someone to say "ok, when are we gonna play again?" because a lot of their value prop comes from the continuity.
There is a really cool Legacy-type game as well (I'm struggling to remember the name, Arcana I think?) where in the Legacy version you basically go through a campaign and develop a character that you can then use as another character to play as in the base game.
You could also design the game so that the destroyed cards are intended to be replaced with new editions.
Impermanence is a tonic to cure obsession.
In that environment, it's probably a lot more acceptable to sell a game that a group will "only" play 15-20 times until the campaign is completed.
With Lego, my expectation is to be able to take things apart, build Model B or create something new. This breaks the design principle and doesn’t do a good job of advertising it’s going to do so.
On one level it bothers me because you should be able to replay stuff, but at the same time it's the experience rather than the game board and there's a lot of ways to spend more than 10 bucks on an hour's entertainment.