-.-
Let's do a fair comparison.
6 bonds + 6 creatures = 36 life. Cost of 30 life minimum.
3 adrenaline + 3 creatures = 36 damage. Cost of 15 life minimum.
Adrenaline is TWICE as good as bonds. Don't get me wrong, bonds kick butt if you have a full field, but in life mono, you can't make a full field. Not easily. Besides, adrenaline is a complicated card, with a table for the amount of damage dealt, over how many attacks, and strange effects when with devourers and arsenics, and even stranger effects with steam machine. The community could use an article on that.
(By the way, here's how steam machine works with adrenaline. If it starts with four attack power (AP), it does it's first first attack as though it was the first attack on a normal 4 AP adrenalinized creature. If you play adrenaline on a cockatrice, it's first attack is for four damage. For it's second attack, it attacks as though it were the second attack on a three AP creature. If you play adrenaline on a frog, it's second attack will be for three damage. For it's third attack, steam machine has 2 AP, and it acts as though it were the third attack of a 2 AP creature. 2 damage. For it's fourth, it's the fourth attack of a 1 AP creature. 1 damage. Then it stops, because 0 AP creatures don't have a 5th attack.
Now let's pretend steam machine was blessed, and then got three additional AP from steam. It's first attack is the first attack of a 6 AP creature, so it does 6 damage. Next it does the second attack of a 5 AP creature, or four damage. Then it does the third attack of a 4 AP creature, so it does 2 damage. Lastly, it does the fourth attack of a three AP creature, or three damage. 6 + 4 + 2 + 3 = 15 damage.)