Yeah...
The legitimate grievances were
- Lack of participation in in the governing process (due to it being a monarchy)
- Limited small-scope censorship
- The presence of a small-scale secret police force
However, the sentiments of
- The Shah is hammering the middle-class in favor of the wealthy elite Americans and Brits (false, the middle class in Iran during that time was the fastest growing in the region, and they had a wealth inequality index score on par with US circa 1950s, and they were actually make more revenue for domestic use via that partnership)
- The Shah is planning on banning Islam
- The Shah is killing protestors by the thousands
- The Shah is planning on bulldozing every mosque in the country
- The False Flag activities that were conducted by the Tudeh party and Islamists, and then blamed on the Shah
- The Shah is secretly working for the freemasons
...those were all meritless claims that spread like wildfire.
That's why the author I quoted before (the Iranian woman who was the Nobel winner), stated that "In hindsight, knowing what we know now, what we needed was reforms and not total destruction of the system we had"
And those legitimate grievances (and the reforms needed to correct them) were in the process of being addressed by way of the Shah appointing a PM who was from their center-left party (who was part of Mossadegh's administration previously), and tasking them with setting up a civilian government, lifting all censorship, and dismantling the SAVAK.
However, the impassioned "revolutionaries" were so whipped up into a frenzy because they believed the items on that 2nd list were true, that they didn't even give it a chance and labelled him a traitor and sent him into exile.
Modern Day Equivalent:
Pretend that Donald Trump finally came to terms with the fact that there were grievances about his administration that were legitimate, and in order to soften his approach and extend an olive branch, he appointed Bernie Sanders to a high ranking position, and tasked him with making the reforms needed to address those issues.
...but, instead of giving Bernie a chance, agitators from groups like Antifa, BLM, etc... circulated a bunch of false rumors about Trump murdering people and planning on bulldozing places of worship, labelled Bernie a traitor for agreeing to work with him, and exiling him to Canada.
When people believe falsehoods of that extreme nature, they're not going to think clearly.
If one actually thought their current administration was doing those types of things, naturally they're going to think "this is messed up beyond repair and not salvageable, not even Bernie could save it"... where as, if their mindset was more grounded in reality, they'd be more likely to give reforms a chance.