I think you do not understand the original poster's point.
Who said that a tennis is "more exciting" towards the later parts?
Who said that the early parts of a set are "doldrums"?
And who said that matches are repetitive, watching 100 000 pro matches does not mean the next will be repetitive?
You see, you have accepted this way of watching tennis - and see no other way to do so, so it seems natural for "color" commentary by the likes of Koening to help, when in reality...
1. Often the early parts of a set can be the most interesting
2. Commentators ruin natural match tension
3.
They can make stupid comments that annoy you
4. Their bias towards a player can get in the way (Koening = Nadal)
5. Their bias towards certain techniques are very annoying (Koening & Goodall's view towards the two handed backhand in comparison to the one hander is childish and shows no analytical thinking )
Perhaps these 5 points explain why some don't like Koening.
I think the best commentator I have heard has been Agassi, Henman or Arias. Agassi, if I recall correctly, has only commentated once, USO 2007 QF Federer vs Roddick, and when he did, he put the other commentators to a shame.
McEnroe for example, despite being a very good ex-player; cannot really comment on the style that players have today due to him having an ancient, and even back then, rare style.
I think sport in general is better with no commentary, a no-commentary button would be beautiful.
John Lloyd makes some good points now and then, during the Aussie open he made a great point about how Tomic was dominating Nadal technically, but often his analysis and commentary is just boring, full of cliches.
Henman I think is better than Lloyd as a commentator. He doesn't sensationalise! He's very classy. During the WTF this year he commentated alongside Andrew Castle, and Castle kept on talking during the rallies,
Henman kept quiet.