If Google called me on it I'd use the same reason they used on me a few years ago when they did it to me which was "everyone does it and what we're doing isn't wrong but we'll stop without admitting guilt".
As much as I was po'd at the response I must admit they had a point. I knew what they were doing. But, there was no concrete proof of Google doing anything wrong since being curious is not a crime in itself and it certainly is not the same as reverse engineering.
If someone here was saying or even hinting at being anything other than curious I would have a problem with it as I'm sure others here would also. But since that isn't the case so far then I say fine, be curious.