I'm telling this from an American perspective. The Middle East is the poster child of the harms of religious nationalism; but that's not a uniquely Iranian problem. Nor does religious nationalism or fundamentalism uniquely imperil normalizing relations with a country - Saudi Arabia has an arguably stronger movement of fundamentalists and religions nationalists, and we still allied with them.

The grandparent asked for "Why does America support Saudi Arabia when Iran is more in line with American values", and in that particular case the answer is almost entirely "CIA Bad", possibly with a dash of "right wingers use other countries' right wingers as an excuse to hate those countries".