BTA Bundles vs Sales - will cheaper than bundle sale take game out from bundle list?

That's actually a good point. Super Hexagon was BTA for one bundle, and it goes on sale for a dollar oftentimes. Should it really count as a bundle game still if you can get it from the Steam store for LESS than the bundle price? Granted the bundle comes with other games, which is the main issue here.

Humble Bundle 8, for example, I'm sure both BTA games will go on sale for 2.50 and the average was around 5, but you still got, like, seven other games with it.

The system is not perfect. But it's just not feasible to discuss and adjust the bundle list for each game individually depending on sale prices. This would only lead to a lot of confusion, tons of extra work for the staff and probably tons of complaints as well.

And 75% off like it is the case with FTL now is hardly abusing the CV system, I would guess that more than 95% of the games given away here were bought as part of a bundle or with 75%+ off price.

FTL is only 75% off, what are you going on about?

As for your Brutal Legend comment, there is currently nothing in place to have games removed from the bundle list once they've been added. I felt I should add that regardless of whether you giveaway a gift or a key, once it's on the bundle list, you receive decreased CV.

No. I bought Bastion for $3.75, when it was a BTA game for at least $5, and it did not add to my contributor value, so I can assume that's true for all BTA games.

Using your Super Hexagon example, the BTA for that bundle was (on average) $6.95. The BTA consisted of 5 games, and if you remove $1 for the base bundle it means on average $1.19 per game. But some of the games are worth more than Super Hexagon on regular price, so taking the price ratio into consideration that particular games was worth a lot less than a dollar as part of the bundle.