WHY was Jesus cricified?

[orangebox21]

So, why was it necessary for God to have Jesus sacrificed for our sins? Now, I know that this whole notion of Jesus' death being "a sacrifice" is stupid,

Why bias a potential answer to begin the question?

and I've already covered that elsewhere, but for sake of this thread, lets assume it counts. Why did it have to happen? By what mechanism does the death of one innocent person atone for the sins of others?

By the very nature of what atonement is.

I was thinking about this and realized that this was something that God either chose to do, or somehow had to do, and either way, it has weird consequences most Christians don't like to consider.

God had to go through with it:
So, for whatever reason, this bizarre self-sacrifice was vital to God forgiving our sins, and he couldn't simply just... forgive us.
It's something to which God was beholden, and something he has no control over. It makes me wonder: from where did this rule come?

From His nature. God is just. To simply overlook wrongdoing would be unjust. God cannot deny His nature.

Conclusion: God is not omnipotent.

A misrepresentation of the definition of omnipotence. Omnipotence excludes God doing things contrary to His character and nature (ex. God cannot lie, doesn't mean He isn't omnipotent).

God chose to go through with it:
God could have forgiven us, but he instead opted to have one third of himself be sacrificed to another third of himself for reasons. Now, this seems stupid (and it is), but I guess I can't complain too much. All parties involved were consenting, even if it does look like some really freaky S&M. Still, the whole charade was unnecessary and overly theatric.

How would you go about proving that 'the whole charade was unnecessary and overly theatric'?

Conclusion: God's bloodlust exceeds his compassion, and he goes out of his way to cause suffering when "solving" problems.

Not true at all. Consider what must occur for a being to be both just and merciful and the same time.