Can't disagree more. I do think the clear conflicts between HBO and the executive producers (there's entire scenes in S4 dedicated to a meta-FU to the corporate demand for telling the violence story and not the maze in field story) led to a more disjointed later seasons than planned.

But rewatching S1 it's clear that the twist at the end of S4 was planned from the very start, which is just wild, and probably the biggest temporal misdirection in the history of film and TV — fitting from Jonathan Nolan, but still unexpected.

And then if you go and see the original Westworld film, the degree to which they were already starting off with such a different take can be even more appreciated. It goes from a film about a robot rebellion where the robots can talk but literally no one ever asks why it's happening or even talks to the robot at all to a series of "if you can't tell the difference does it matter?"

The whole point

The original narrative IS the narrative about it already being a simulation with the 'guests' also already simulated. It's just that it doesn't appear that way at first because it's a gradual reveal across multiple planned seasons that's got its own smaller first season set of reveals along the way. So when you realize the twist in the first season you think "oh, now I'm caught up with the events" and when you see Bernard is a machine of an earlier human you think "oh, this is the exception and not the rule." But there are details in the first season that can only be explained by the events revealed in the later seasons.

S2 has terrible pacing and I do think there are various issues with how S3-S4 progresses in certain arcs, but the broad plot was very clearly planned from the start in hindsight, but HBO had it out for them (look at how quickly after the cancellation the series wasn't even available on HBO's streaming properties), and unfortunately they didn't get the S5 to reveal just how much had been layered in earlier on.

TLDR

TL;DR: You were always supposed to have been watching the civilization level fidelity test, not original events playing out.