I thought the great thing about iPhone was that during warranty or Apple Care period, any serious hardware problem is an automatic 1-1 exchange.
Ignoring the debate between environmental sustainability versus Apple’s strategy of preventing 3rd party repairs, having your phone in the repair center for a few hours or maybe 1-2 days could be a huge inconvenience for some ppl. Apple should come up with a bundle of buying 2 phones at a certain discount, to “encourage” demanding users to have a backup iphone.