Lets be fair here though. Google encrypted their PRIVATE data links based on the Snowden reports. Most people/companies would assume their p2p (point to point) links would be private, which to be honest is a fair assumption.
It used to be a fair assumption, but now everyone has moved to encrypt any connectivity that goes outside of your physical oversight.
Some people are paranoid enough to encrypt cross connects within the same facility that run between cages or floors, which is a sad state of affairs (but, in my opinion, sensible).
Yes, the sensible solution is for all communication to be encrypted as tools and services get up to speed on that.
There is nothing to be gained by continually making judgement calls about which communications need to be secure and which don't. Like a lot of other technology, security needs to become pervasive so we can all take it for granted and worry about productive problems.
Only if they already have illicit access to the systems in question. In which case, considering Dropbox doesn't actually encrypt data at rest, it'd be much easier to get the data at the endpoints than in transit.
Not even remotely comforting. Talks all about how employees "are prohibited" from accessing your data, but that's unrelated to whether they're capable of doing so.
I much prefer the privacy policies of more secure services, which tend to say things like "we do not have the ability to access your data under any circumstances".