Rob,
Certainly your point of view. Interestingly we get more complaints about not saying enough in this regard. Cabin crew will often tell us that people are asking where we are, etc.
I don't think it is a case of pilots being "new to the job", or necessarily "trying to impress." I do sometimes remind new pilots that they are carrying people, and it is important to communicate and within the limitations, interact with those passengers. It may not be to everybodies liking, but communication is an important tool, and how it is employed varies depending on the recepient. ATC, the cabin crew, the passengers etc. It is therefore important that it is practiced and employed in a frequent and sensible manner.
Given the constraints of security, time, etc. It is often difficult to use the communication tool as effectively or productively as you might always like, but nevertheless it is important that it is employed. Of course communication used properly is one of the primary components of "trust" so its absence can't really be used to imply anything particularly positive in this regard. A safe, regular and relaxed flight is what everybody wants from any journey, and the communication employed should be used to that end.
Jipperty,
Every Eurostar train I have ever been on, do have (cabin) crew on board. However passenger carrying commercial transport aircraft have legislative constraints placed upon them regarding the conveyance of passengers. The difference in the nature and environment of the operation means that aircraft passengers are required to have seat belts fastened at various times, and to be briefed at various points in the operation. The legal requirement for this compliance falls to the aircraft commander. Obviously it is impractical for the commander to ensure this compliance, so it falls to the required cabin crew to instruct, ensure and report that compliance.