What do you mean? This whole thing started because they ignored Iranian stance on dual nationality and the diplomatic situation in general.
I thought she was visiting her family with her daughter and was arrested?
Right? I'm not sure which bit you don't follow.
She took her daughter, who has UK nationality only, and travelled, as a dual national (some dispute about which passport she was on, i think) back to Iran. So she and her DD presented as a British, or Iranian/British group.
Sh must have known her work for BBC and Reuters put her at risk from the Iranian government, she certainly knew that dual nationality is not acceptable to Iran. In fact, it's an affront.
She took a risk. She should be able to travel freely, visit family etc, of course she should.
But anyone with Iranian or ME connections know what the Iranian government do and do not like. Dual nationals had been hitting trouble regularly.
I hope the Ratcliffes at least serve as a cautionary tale and thus help to prevent similar situations, because having BoJo as PM isn't hopeful for diplomatic solutions.