Is a lecture by Bill Gates (or anyone else) good television?

I don't often repeat blogs verbatim, but watching Bill Gates giving this year's Richard Dimbleby Lecture (HERE) reminded me of a question I asked two years ago that still baffles me and is still awaiting an answer, namely: 

Why does the BBC commemorate Richard Dimbleby with a televised lecture?

My thoughts from two years ago remain pretty much unchanged:

'Last night's Richard Dimbleby Lecture on BBC 1 was delivered by Michael Morpurgo, the latest in a long and distinguished line of famous people to have done so every year (except four) since 1972 (full list HERE).

'But what baffles me about this annual event is how and why the BBC ever decided that the most suitable memorial to a celebrated broadcaster would be something as ill-suited to television as a lecture.

'Wouldn't an annual Dimbleby Documentary, Dimbleby Debate or Dimbleby Interview have been a more fitting way to remember a current affairs journalist? After all, these were not only the kinds of things he was best known for, but would have come across better on television than celebrities, many of whom have little or no experience of lecturing, standing behind a lectern and talking for rather a long time.

'Given the BBC's increasing reluctance to show even very short extracts from political speeches in their news programmes (on which there's more discussion and links HERE and HERE), it strikes me as rather odd that the Dimbleby lecture has been allowed to carry on in its original format.

'So far, I've been unable to find out anything about why the BBC (or who) decided in the first place that a lecture would be the best way to commemorate his life - and would be interested to hear from anyone who knows something about its history.'