In a quick read in Wiki it does appear the attack was unnecessary and incompetently planned and led. It's not much comfort for the Aussies to note there was plenty of that in all the WWI armies.
Gallipoli is a focus because it was the first large scale action in which Australians were involved (although not, as some people believe, the first Australian action - 2000 Australian troops as the Australian Naval and Military Expeditionary Force (AN&MEF) had captured German New Guinea in September 1914 - New Zealand troops had conducted a similar operation to seize German Samoa. In terms of losses, though, while Gallipoli was not a small campaign, it was smaller than some that came later.
Almost worse, “some” of the Aussie troopers did get through the German lines and out of the machine gun fire from in front of them. (Several hundreds of the thousands who attacked initially)
Then they were abandoned to the Germans over the next few days by the British command. True, the Brits faced communication and coordination problems with the own trenches, much less through to the front zones where the furthest forward soldiers were, but the Brit’s did abandon living men behind enemy lines, and the remaining Canadians will not forget.
The battle of the Somme was fought because the French were losing at Verdun (and losing there would have seriously broken the front); they asked Britain to relieve the pressure by drawing off German troops, and they obliged by pissing away thousands upon thousands of lives in an attack that was never designed to succeed - just to take German troops from Verdun. Over 60K troops (mainly British) were lost on the first day, but it worked - pressure on Verdun was relieved, and France remained in the war. A year later, the French troops mutinied in response to the callousness of the high command that frittered away their lives in similar futile attacks. The mutiny was kept from the Western press at the time, since it would be hard to ask Americans to die for France while their own soldiers wouldn’t do so anymore.
A lot of the apathy by the European public to WWII had its roots in cynicism bred in WWI.