I'm confused on the point you are trying to make. Can you explain?
I'm saying that our cycle didn't witness the synthetics wiping out all life, so we would have no reason to attempt to stop synthetics in our cycle.
Not saying that the Reapers were right in attempting to stop this.
Would you agree that you don't have as much emotional attatchment to a book you've read as opposed to a game which proposes to offer a completely unique experience based on choices and requires you to win 3 games?
If it was a book I wouldn't have a problem but it's a bit of a screw you to players, not to mention adding insult to injury by begging you to buy more DLC .
EDIT: It depends on your mindset to gaming as well, do you pretend to be the character or view it as an interactive story/movie?
Both. It just depends on the game really.
The entire game proves otherwise. Even the AI on the citadel in the first game is only acting hostile because of laws prohibiting his sentience. Not once do we see an AI attack another being of their own free will or from self defense. The Geth only did it when they were reprogrammed. Via the in game universe, there is zero reason to suspect we can't work together. If this cycle was so different it MUST be for a reason right? Shepard actually made it to the god ai child. So something must have been off the entire cycle. Think about it, the Protheans and all other civilizations developed AI prior to the point in this cycle. They got involved in their own wars with them and then the Reapers stopped them. This means we've made it further into the cycle, and it's different. If we were the exact same we would have already been emroiled in a Synthetic war like the other cycles which "proves" this kids point.
I'm not really sure where you got this information, as I don't recall a war with synthetics during the Prothean cycle being mentioned.
Keep in mind it also took entire cycles to come up with the designs for the Crucible, so no other race up to the Protheans may have known what exactly the Catalyst was. And keep in mind that they were too late.
Then going back to the working together argument. Your throwing out all reason to suggest humans and other organics can't socially adapt and learn. That would be like seeing primitive slaver humans massacring each other and saying the species is doomed and never going to learn. Yet we did and we're here form a primitive culture to this. It's suggesting we're incapable of learning and working togeather. Despite the fact that our entire cycle is different right form the get go. It's been made very clear by the Prothean they had their own troubles. The ai kid must not be completely lying because he has to have some basis for a pattern. So then why weren't we fighting synthetics? I believe it's because for once something different happened. Whatever scale that might be.
Not really, just pointing out some possibilities. Humans will always be evolving, but the problem arises when synthetics evolve faster.
As to why we weren't fighting synthetics? Because few had been developed. Sure the Geth have the numbers, but they were just off minding their own business. Keep in mind that they WERE actually hostile to anyone who ventured into Geth space, so we were kinda fighting them, although not in all out war.
Also, a great deal of the Prothean's troubles were due to the nature of their society. Javik mentions that the races never worked together during the Prothean cycle.
This is if you believe anything this kid who is CLEARLY a Reaper says. I mean he even goes on to say us and we and it gives him away as being a Reaper. The fact that Shepard can't question any of this is what bothers me. It's just the tip of a big iceberg in why this ending makes no sense. Not one lick. Oh and then blue/red/or green space magic makes everything better. Weeee and your entire gathering of your army was for nothing. Why the hell did we even bother keeping track of that stuff if it didn't matter? The game makes no sense on all levels.
He really didn't need to question it at that point, since he could either just go with it and stop the Reapers, or let them kill everything. I mean really, the massive fleet you spent the game building is getting destroyed, thousands are dying every second... Why would he stop to chat?
And the shock wave is suddenly magic, but mass relays, biotics, and such make perfect sense?

Edit
And another thing, the whole games message is that we can put aside our differences and work together to accomplish great things? So suddenly we're incapable of doing this? We've apparently done the impossible already. If we did it this entire game, then why can't we make friends with the Geth? I don't get it. They've made it adamantly clear they just want to do their own thing. And given the luxurious position they were in (building a dyson sphere) why would they ever care about some inferior organic races? It doesn't make any sense why they would go all ape [censored] and kill stuff.
Did you ever think maybe all the other synthetics are [censored] up in the head because no one wanted to talk and give them the chance? Who said they started the wars? This ending leaves so many unknowns this debate is pointless. Which is why we need a more final ending than this. I never said it had to be happy, just make sense.
That's the point. The Catalyst specifically states that we cause chaos. We kick the hornets nest so to speak. The Quarians were afraid of their own creations, so they tried to destroy them. If they had accepted the Geth into Quarian society? They would never have had to leave Rannoch in the first place.
Also we're winning this http://www.anologhype.com/video-games/playstation-3-news/amazon-offering-a-full-refund-on-already-opened-copies-of-mass-effect-3/. I didn't think I would see this either. While not a full out victory, it only strengthens the movement. Roughly 79-85% of gamers are unhappy with this crap ending. This is a pole conducted on so many sites over and over again. It's a good sample size to extrapolate to the greater population of gamers. Not necessarily casual gamers mind you, though perhaps some of them are mad at the ending too. I'm so happy I want to watch Mordin http://www.youtube.com/watch?v=bj0iJtgHOCI
The sense of entitlement exhibited by this is staggering, not to mention disgusting.