You can always encrypt on the client, yes. But it is surprising that an entity such as Google doesn't understand that links between datacenters have multiple points out of Google's control where traffic can be intercepted.
ECHELON was an open secret, with EU parliament reports. We knew how the 5 members avoided the legal problems of spying on their own citizens - A just hands B, C, D and E a list of names to spy on.
No, this is HN, they're not supposed to get any love here.
I'd suggest .NET/C# myself. It doesn't have the new flavour of the month feel, but there are some interesting things happening, and it's a solid platform with a bunch of serious, good choices for developing websites and applications. Also, nice documentation and an excellent toolchain. The downside of course is cost...
That said, language/environment etc all should come down to what the OP is trying to achieve - there are a lot of things that there are better alternatives for, but for general purpose webstuff, it's usually a solid choice...
What's most worrying about this is that Dropbox is injecting itself into processes like NotePad++ and Firefox that have nothing to do with shell extensions.
Either this is lazy coding, or there is some malicious intent to spy.
It makes like a bit more complex, but PGP can be used for mail and here's how to protect GDrive files: https://news.ycombinator.com/item?id=6644888
Remember these revelations date from a year or two ago, who knows what they're up to now?