I chose to quote this passage from the article because it's true, and it's a pet peeve of mine. I can't stand to hear actors reading other people's poems. That's because actors have a tendency to act poems rather than read them. Every time I have heard a professional actor read a poem, say, at an awards ceremony because the actual poet couldn't make it, the result has been a bombastic, Pollyanna massacre of the poem. If a poet can't make it, please don't bring in an actor to recite the work. There are probably any number of poets in the audience who can read the honouree's work just as well, if not better. Most likely better.
We do not, for instance, dramatise the emotional events of a poem as if they were unfolding before the eyes of the audience. We have written the poem. Now we are reading or reciting it. Something about our manner should never forget that we are in front of an audience, presenting something we have written. We may become emotional, but not to the extent of - say - slobbering and weeping and wiping our noses on our sleeves. We may be exuberant and spontaneous, but not to the point of spontaneous combustion.
Certain tricks of the radio actor's voice are forbidden to us - funny little gargling sounds or strictures of the windpipe, conventional ways of signalling that there's an emotional passage coming up. We don't like these vocal athletics anyway, when we hear actors reading poems, and we like it even less when we witness other poets moving in that direction.
And why not listen to James Fenton read his own work? Even if he tends to emphasize form over content when he reads, you might learn something.