That's what Steve Jobs used to say and that's why Apple phones were 3.5 inches until he died. Who uses a 3.5 inch phone now? In fact small phones basically don't exist anymore. There were credit card or cigarette lighter sized phones that weighed under an ounce but they were 2G GSM, so now they are e-waste. There is nothing to replace them. Meanwhile the Unihertz Tank 2 weighs about a pound (22,000 mAH battery) and it's imho attractive, except too expensive.
I think it’s important especially because phones have gotten larger on the x and y axes that they remain light and small in the z axis in order to maintain pocketability. There are very thick phones with giant batteries out there for people who want that, but I think Apple has been striking the perfect balance.
They are not that fragile if you don't drop hard. Never used case for A50, it still looks almost new after years of active use. But for iphone I got a thin case, to protect popping out cameras and to make it look cool. Main concern is thieves if I travel somewhere, not the physical damage.
Unless you drop them very hard, cases are not needed anymore. Been using a Iphone 12 pro max for 4 years without a case, I don't even look twice and I drop it from the table.