Edit: - wow - sorry, that got long…
Ah, ok, I get you - yeah, purge as ‘challenge’ but with a ‘reward’ to repay what it (may) take from you. I guess I’m also viewing it from more of the singleplayer perspective - the virtual server doesn’t need ‘clearing’ in the same way as on a real server, so the purge doesn’t serve that purpose. (Plus I’m a builder, so never a big fan of being ‘punished’ for playing how I want to play
).
The challenge part I get (though, no purge I’ve had has ever felt that challenging - for a variety of reasons, not least the number of ‘failed’ purges I’ve had for one reason or another - best one was a purge that spawned properly in every way except they spawned on an island that wasn’t connected to my base in any way
) - I like to set my own challenges, but external challenges are always a good thing to have in a game. But I do also know what you mean with the surprise for many new players (a friend got repeatedly wiped when starting out) - I guess I came in with a little more understanding of what to expect, even if I didn’t know what to do about it - I’d watched Neebs Gaming, so I had at least some idea of what not to do 
I see what you’re saying about lowering the reward making the mechanism unbalanced - not sure whether I agree or not, I guess I never really cared about the purge thralls I did get (possibly coming from never having got the right ones, of course…), so the reward never felt that meaningful anyway. It’s a weird irony that I’ve probably had more reward from purges since the change than I had before (t4 taskmaster with 300% speed boost - I didn’t even realise how good he was till I picked up a standard t4 and discovered they only give 200% - and, on singleplayer, taskmaster speed makes a big difference since there is no ‘leave them overnight’ option).
But is this actually a problem? If people who don’t enjoy the purge (again, I’m back to enjoyment, but that is kinda the point of playing a game - the challenge part is good, but surely only if you enjoy the challenge to at least some extent?) choose not to engage with the purge, who loses?
I’m really not sure on this one - so, to argue against myself a bit, I can see that it could be easy for people to skip the challenge because of the lack of reward and wind up feeling the game is missing something (they might actually have enjoyed having the challenge there). It is the constant danger of sandbox games - it can be easy to avoid the tougher stuff only to find that you’ve actually made the experience less enjoyable as a whole.
But then, to go the other way, is that not still player choice? You can still choose to face the challenge, and get the enjoyment from it (or the enjoyment of having overcome it - which is probably more where the enjoyment lies with challenges), there’s just no longer active pressure ‘forcing’ you to do it as the only way to get (a chance) at the desirable thing (in this case thralls).
Previously we were incentivised to take on the challenge, but those that did not want to had no choice if they still wanted access to certain parts of the game. Now the incentive is reduced, but so is the pressure on those that didn’t want it. I’m genuinely not sure which is better (which is what makes getting your perspective so interesting
)