It’s not about making things look cool. Yes, that is a nice bonus, but this is really a design decision aimed at making more money. You want, no – you need – to boost conversions.
Good news! The solution is easier than you may think. Start using larger images (larger screen dimensions, not download sizes). They consistently deliver higher conversion rates.
Whether it’s a site focused exclusively on sales, or one that’s just looking for sign-ups and to capture visitor information, increased image sizes have been positively correlated with increased conversions. Naturally this has gotten the attention of big brands and e-commerce sites alike.