Per Google Blog, changes are:

Google Flights:

• New features are active on mobile now, will be available for desktop later this year.
• Tapping on "Dates" opens a calendar view of date combinations with lowest and highest prices highlighted.
• Or for trips of X days, price graph will show you how fares vary over time:

For hotel searches:

• When searching dates for a specific hotel, nightly rates are displayed in calendar view.
• And you can also see how rates change over time:

Airports:

Google now lets users see an interactive map showing all airports near a destination, with distances. Intent is to enable users more easily to find the cheapest flights and make intelligent distance/price tradeoffs.

And there's also similar functionality for hotels:

Google says they've made these changes because 3 out of 5 people (in a sample of 467 Americans aged 18+ taken in July 2017) said they'd be open to changing travel dates if it would save them money.

That's a pretty thin sample on which to base an initiative as expensive as making these changes must have been for Google. So I suspect that along with this altruistic motive Google was also motivated by research that predicts more revenues for Google from these changes.