Surely Google knew they were saving the packet payloads, even if they didn't have any intended use for them. That is not the kind of detail a programmer can simply overlook. Calling it an "accident" is certainly disingenuous. The only accident was not realizing that people would care so much.
There are several comments below the article which noted that Google had turned over data to external French auditors, who reported finding passwords, emails, and other sensitive information in the WiFi data captured by Google. Personally, I would be more worried by external auditors having access to the data than Google.
An interesting thought: should we blame Google or should we blame the unencrypted wifi hot spots?<p>The fact that it's so easy to sniff unencrypted wifis should be more worrying. I mean Google turned over the raw data, I may do the same and intentionally sniff even more data, steal everybody's password and not admit it.<p>Like the author said, you can punish Google, but that won't make those hotspots more secure. And you never know when will a real evil guy come to the neighborhood.