[yyyk]

Weirdly, I tend to blame regimes shouting 'death to America' for bad relations with the US.

Remember that the nuclear deal only dealt with nuclear matters* , all the other regime behaviours (hostage taking, supporting terrorists, missile development, etc.) remained. Stable relations between US and Iran are impossible without the regime changing its ways, the regime has no reason to change so long as the deal exists, ergo there won't be stable relations.

* Even the nuclear terms expire in about a decade, leaving Iran free to do whatever. There used to be a similar deal with North Korea, and we saw how that ended up.

[potatoz2]

I tend to look at actions, and the US (in particular the current administration) bears a large part of the blame. The Iranian government is despicable, but so is the one in Saudi Arabia, yet the US has no problem supporting them. The North Korean government is much worse, but the US negotiates with them. Historically, the US has had no qualms associating with authoritarian countries. There's no intrinsic "reason" for the poor relationship, except realpolitik balance of power.

[inamiyar]

Maybe the answer here shouldn't be reconcile with Iran, but stop supporting Saudi Arabia... (or so, didn't really think this one through)

[yyyk]

SA and NK are vile, but they are not revisionist powers like Iran. It's not a surprise the Iranian regime's attempts to expand its hold across the region would lead to opposition.