The way people view television has changed. Streaming services have meant binge watching has become the new normal for a lot of people (myself included).
Since the first series was released in one go, it shouldn't be a surprise that people have reacted angrily to this seemingly forced restriction that seems not to have been known about in advance (I don't know if this is true of not, I've been avoiding all mention to eliminate spoilers. I'm only going on what people are writing).
As for whether it is fair to review bomb a show for something that is happening outside of its control, well that is another matter.
On the one hand it gives a false sense of the quality of the show which risks damaging both its reputation and potentially its future, on the other hand it gives an instant response to the marketing people at Amazon that this change isn't universally welcomed.
I disagree with the comments elsewhere regarding entitlement.
Sure you could view it as that if you were to imagine that everyone complaining is some 15 year old kid that lacks experience of how television is broadcast, but as a middle aged man that started my TV experience with just 3 terrestrial channels and has watched the way television has changed over the last fifty or so years, I also think there is a level of unfairness that people have the right to react to (though I don't agree with the review bombs).
Being angry because we are powerless to help the things we love is a perfectly natural behaviour. Is it justified in this case?
Well that entirely boils down to have you consume television now. If you - in addition to watching streaming shows - also watch broadcast TV, then your brain is still hardwired to the old system.
If on the other hand you no longer have a TV, haven't watched broadcast TV in years/at all (in my case, not since 2002), then you are being forced to use a system that places artificial restrictions on how you view that content.
Would you all sit idly by when Apple announces your next phone will require a 3 minute connection sequence to access the internet? Well that's how it used to work. Millions endured that without complaint in order to consume the internet, so why not you? Would you be entitled for complaining?
Well we know companies can choose to stream TV shows in one go if they want to. Not doing so is a choice. People have a right to react to that choice.