Israel gets to blow up hospitals that are used by Hamas. Hospitals are only protected as long as enemy forced refrain from using them (other than treating wounded).
Israel also gets to kill Gazan children who pose a threat to their forces. Which unfortunately is anyone who is armed or otherwise performing combat duties. Hamas makes use of teen soldiers, so unsurprisingly Gazan teens get themselves shot.
As for the total amount of explosives used.... Obviously a rich country like Israel is going to use technology to avoid getting their soldiers killed. Frankly I think they should have not put any soldiers on the ground inside Gaza, and just bombed it from the air. But Israel is sacrificing a lot of men to avoid killing Gazans.