1. So you'd rather have a no-brainer Hollywood Ending Option than a difficult decision.
2. If you choose destruction, both synthetics and Shepard are supposed to die. The kid, however, is a textbook example of the unreliable narrator, I've explained this in a previous post, but you would only know this if you played the story. And guess what, Shepard survives, and we don't actually see synthetics dying, just Reapers.
3. Apart from that, there are two specific conversations in the story (one with EDI and one with the Geth) where they specifically state they are prepared to die if it is the only way to destroy the Reapers. EDI even adjusts her self-preservation protocol for this, right before the last mission. Once again, you wouldn't know this, because you haven't played the story.
Except, there is, and it has been tried. The game clearly establishes that all who came before you who believed they could control the Reapers (including the Protheans!) turned out to be indoctrinated. There is even a record of the Crucible being completed multiple times throughout galactic history, and it was never used to destroy the Reapers because all who tried to use it, ended up being indoctrinated.
There are multiple conversations in the game about controlling the Reapers and every character on your side (including the Last of the Protheans, Anderson, Hackett and just about all of your squadmates) claims it is an illusion to think anyone can control them. The one and only character in the game who is in favour of the 'controlling' concept is The Illusive Man, and the game establishes/exposes him as being indoctrinated on multiple occasions.
Literally the only reason you have to believe that you will be able to control them, is the kid from your dreams suddenly appearing on the Citadel and telling you that you are not being controlled by the Reapers.
You could think "But I'm TEH Shepard!", however, only minutes before that happens you are telling the Illusive Man that he "wants power that is too great to be wielded", and: "What if you can't control the Reapers? Are you willing to bet humanity's existence on it?", upon which he realizes he is indoctrinated, and kills himself.
And then there is the 'vision' of Anderson shooting (choosing the destroy option) when the kid explains the destroy option. How many hints do you need for what is the right choice?
And again, you wouldn't know all this if you haven't played the story. It is all established thoroughly in the story, and the only reason you have to think otherwise is the kid, and the idea of "But I'm Shepard!"
Aside from that, what does 'controlling reapers' even entail? (Besides the fact that Shepard is controlling them when dead, wth?) So they'll stop harvesting now, and do what? Creative gardening? They can't even 'procreate' without harvesting organics. Dead organics pulp is literally what their blood is made of.
Except the game does not establish that there's any way to properly control the Reapers or 'merge with them'. Rather, it goes to lengths to explain why thinking that you can control them is an illusion, and the idea of synthesis has never been shown in any favourable light in any of the games.
As for the Synthesis option, the game establishes the following:
1. Saren wanted a 'union of Man and Machine, the strength of both, the weaknesses of neither', etc. Turned out to be indoctrinated, shot himself. Kind of the main point in the first game?
2. Humans + Reaper Tech = Husks
3. Only bad guys are in favour of Synthesis, Saren and Kai Leng.
4. Synthetics and organics can co-exist peacefully, as Shepard proves by uniting Geth and Quarian, one of the main points of the story, again: if you've played it.
Aside from that, who is Shepard to gamble with the idea of playing God and turning everybody into shiny happy robot people with green space magic? Let's face it, that option isn't even remotely realistic, and I think the phrase 'too good to be true' applies here.
Does the phrase 'better safe than sorry' perhaps make any sense in this context?
Why believe a kid whose 'solution' to the 'eternal conflict' between organics and synthetics is to let synthetics periodically harvest advanced organic civilizations? That is circular logic of the worst kind.
The only thing that gives any credibility to the kid is the Prothean VI on Thessia that mentions that the Protheans suspected that there is a 'master' to the pattern, and they believe it's not the Reapers themselves. He does not explain on which they base this, though. But at the same time it leaves open the possibility that the pattern is caused by the Reapers themselves.
The fact that you get 'Reaper eyes' (like the Illusive Man has) when you choose control or synthesis, speaks volumes though.
They are lying about several things in order to make you believe synthesis and control are the most favourable options. The Reapers want Shepard on their side, as a symbol. This is all too evident from Harbinger's (who is the Reapers' leader) words: "You do not yet realize your importance in this, Shepard. Join us! Embrace Perfection!", etc.
If they don't give Shepard the destroy option, Shepard will realize something is wrong and break through the illusion.
What do they have to fear? No organic has ever withstood the effect of indoctrination upon completing the Crucible.
The fact that the kid (who repeatedly refers to the Reapers as 'us') does not stop you when you take the destroy option, supports the idea that it is all an illusion.
If they don't show it happening, it's even weirder because there is no closure at all. And if they show something different happening, the illusion is dispelled. They obviously wanted to leave all of this ambiguous so people would debate this just like we are doing now. Hell, they even came out and admitted they purposely made it controversial.