My first impression of these logos compared to the old ones, is that the old ones represented the application (they look like mail, a calendar, a document and a camera in a speech bubble; only Drive doesn't look like anything). The new logos represent the company: you primarily see the Google colours. They look less like what the application does.

If they wanted more google branding, more recognisability that these are all apps from Google without undermining the recognisability of what the app itself does, maybe they should have left the logos as they were, but added some consistent Google colours as a border or background. Then you can recognise them as mail, but from Google, calendar, but from Google, documents, but from Google. Now they're all just "some Google thing".