The vast majority of my colleagues and friends on 7-10 day itineraries, manage quite well without checking luggage.

While checking vs. not checking is a matter of personal preference and not really a debate, it is entirely incorrect to suggest that checking luggage is an integral part of air tickets. That may have been true 20 years ago, but it is not true today. In the simplest terms, many businesses --- and they are the core of BA's business model --- are looking for the cheapest seat from A to B on a carrier which provides a large network. Thus, the corporate policy may pay a premium price for BA over an LCC on short-haul because it obtains a significant corporate discount which really matters on long-haul. But, it sees no reason to pay for checked luggage as included in a ticket when it can do so on the rare occasions when its people require that feature.

Add into this the simple fact that short journeys are increasing. There was a time when a 10-day trip to or from the US was considered a miracle. Now, 1-2 days is easily doable.