I disagree. Stopping to regroup for a new plan implies alternatives. A new plan implies that manuver, surprise, or tactics could win a campaign with less cost. This is a small island with a determined enemy well dug in. The only alternative would have been to abandon the invasion thereby handing the Japanese a victory.
Further while Nimitz was "regrouping" the Japanese would have been too. Additionally any amphibious landing means that the invasion fleet is necessarily locked to a stationary fixed location making an excellent target. Although the Japanese surface fleet was finished by the Iwo Jima invasion they still had more than 150 subs and several hundred planes that could have reached Iwo and the invasion fleet. Consider that the loss of a couple of carriers might have meant the deaths of thousands of sailors while you are regrouping and second guessing yourself.
Too many Marines died unnecessarily.
This you may argue but the only alternative was not invading at all. Perhaps the intelligence was poor but its the best that there was in 1945 when the decision was made. Lastly I will point out that although it is trite it is also true that war is won by fighting the enemy where he is. By 1945 the next steps in the war with Japan were necessarily going to be bloody. Warfare is a hazardous undertaking. Thats why those that follow that trade of arms are referred to as heroes.
As a 19yrear old marine in I Corps (Vietnam), I saw heroism. But I think it's our obligation to question tactics after the fact. Never did myself or my brothers not fulfill their duty. But to study the history of battle, in my opinion, is not arm-chair quarter-backing. It's our duty. Semper Fi.