Not if the public's reaction is "Aah, nuclear bad, no more nuclear!" instead of "hey, idiots, you need to change your specs for seawalls".
> I'm sure they thought the seawall was high enough when they built it.
The problem was that their definition of "high enough" was wrong. That's not a matter of reactor design, or even an issue that's specific to reactor design; it comes up in any issue involving cities or facilities near seacoasts (for example, specs for levee heights). But in every other area that's affected by this issue, the response is "you need to change the specs for how severe an event the facility needs to withstand", not "stop building this facility altogether". Nobody argues for abandonment of all coastal cities because some levees aren't high enough.
> Why are we now so sure we couldn't make a similar miscalculation?
Who said we were? There is no such thing as zero risk.
No, they thought they could site the backup diesel generators and switchgear behind a seawall that turned out not to be high enough when a tsunami came through. None of the issues at Fukushima had anything to do with the design of the reactor itself; in fact, the reactor was obviously significantly over-engineered given how well it withstood an extended loss of backup cooling.