Even if the match or the event is exciting I could not watch it without these commentators they add value excitement and information to the matches they are the voice of the match or the events, even if you don't know much about the sports that you're watching you'll get insight and information by just listening to these commentators.
And they are good in most of the sports too, I mean they know more than the srpots such as strategy they are using the ability of the players and many more that's why sometimes if I am not familiar with the match I rely on the commentators about the stats, etc. of the team or the players.