Google wants us to get out of our own way
Google is increasingly doing everything they can to get marketers to get out of their own way and let the machine optimize. The vehicles for that machine learning-driven optimization are Responsive Search Ads and Responsive Display Ads.
Their newest way of getting more people using more Responsive Search Ads is to automatically import headlines and descriptions from existing text ads in the same ad group.
You can read more about this and related changes at Search Engine Land, but the TL;DR is that Google's clearly convinced the old school of highly controlled search ad campaigns largely underperforms relative to these new ad types.