In hindsight, yes they should not have built a nuclear power plant in an earthquake-prone area like Japan. But there are plenty of places that are completely safe to build nuclear reactors, and given the alternatives, we should lend the advantages credence. Hopefully the whole debate will be moot when either solar/wind gets to a certain point or we figure out nuclear fusion.
The location of the plant, next to the ocean, placed it in greater danger from the tsunami. Had the plant been located up higher, above the centuries-old tsunami warning stones, then there maybe would have been a different outcome.
My understanding is that the plant was built seaside to make use of the ocean water for cooling. There are definitely alternatives to this, but in the cost analysis, how many other tradeoffs re: the expediency and safety of nuclear technology are we making that are going to prove to have been in the wrong direction? What is the failure cost going to be?
No place is "completely safe" to build a nuclear power plant (or anything else!). If nothing else, no matter where you build it, it is not 100% proof against attack by military action or evildoers.