Don't watch it then if you don't want to be spoiled lol? I've watched less than a couple hours of streams and have no plans to spoil the game. You can make the choice not to spoil it for yourself. Others want to, and it may influence their decision to buy the game.
Honestly, the people against the streams are indirectly against HBS making more money off the game. This is how you get the word out about your product now. I'm sorry if that bothers people, I want to play the game too, but I also want HBS to make as much money as possible off BattleTech. And streams like this is how you do it.