I'll go for the most simple answer possible.

No.

I don't think there would be a tangible benefit.

Also I'd prefer you just start banning people who reply with "+1", "this", "/thread" or any such variants

While I do indeed hate people saying "This ^" *Looking at you THE1* I would much rather have that than a Like Button.

Yes!!! There should be a like button! I don't really see any real disadvantage imo, and it may even help the lurkers get used to these forums more if they can see what the community likes :)

Hell no. My Reasons? Just look at Youtube and N4G.

No

The new users would be terrified though if critical posts gets upvoted in their threads.

The like button would not only boost self esteem...

I'm not sure how that last part makes sense? XD

Nor the first part, THE1. Please explain because I'm confused with your post.

Also, I think I smell a typo possibly?

Most people here are never that harsh on new users unless they're posting blatent flamebait stuff. I don't think it'll hurt too much but I see your point.

Those saying that no good forum uses the like button, take a look at Westeros, which is what I'm really basing this on:

http://asoiaf.westeros.org/

Here's a relatively spoiler-free thread (though if you want to avoid spoilers completely, just look at the bottom right of the posts); http://asoiaf.westeros.org/index.php/topic/63913-abbreviation-translation-for-n00bs/

Here's a great example with both upvotes and downvotes:

http://www.zam.com/forum.html?forum=21&mid=1200547619179458414

But that's very risky.