Maybe you should take a look at this. I don't know how much influence this guy has in the halls of government. Wikipedia would seem to imply that there is a considerable faction of their civil and military leadership which is very much interested in destabilizing American politics by inflaming racial tensions and supporting any and all dissidents.
Russia should "introduce geopolitical disorder into internal American activity, encouraging all kinds of separatism and ethnic, social and racial conflicts, actively supporting all dissident movements â" extremist, racist, and sectarian groups, thus destabilizing internal political processes in the U.S. It would also make sense simultaneously to support isolationist tendencies in American politics."
You're generally arguing that it would be absurd for Russia to do these things, and it is absurd if you implicitly reject the notion that they would do so. Otherwise we can spin a pretty convincing narrative. Putin certainly has no love for Clinton, and is interested in increasing his share of world power. Since a direct military confrontation is a foregone conclusion, they turn to information and cultural warfare, and the well-worn tools of the spy trade. Hacking the voting machines directly is out of the question, but the majority of the people in the country are dumb enough to think that the major parties represent their interests, so the goal becomes controlling the narrative. Bribing journalists would be costly and prone to exposure. It's best to give them a story that is big enough that they have to report it. Hacking is deniable, doesn't require subverting anyone in a foreign nation, and has a fairly low cost and risk-reward ratio. Given the goal of destabilization, hacking a major political party becomes an obvious move. We've actually seen this exact scenario before, where state-level intelligence agents were caught attempting to hack the Democratic National Committee. We can probably assume that the intelligence interests between the major powers reflect the perceived threat level of the other powers, so it's probably safe to say that Russian hackers would be employed against US and Chinese targets primarily. It's likely that hacking attempts are made against the two major parties continually, but especially when the stakes are raised during an election.
So you're Putin. You exercise a great deal of power, but you are still ambitious. You don't exactly wake up every day thinking on how to knock the US off its pedestal, but it's never really far from your mind, and any ideas along that line will always find a willing ear. For Putin, this is nearly a foolproof solution, the only real consideration is what the US will do in response. You've already invaded the Ukraine and not drawn a military response. So why not do this?
So we have an established motive, an inarguable opportunity, and all of our intelligence agencies saying that there was at least some degree of influence. If Putin did not specifically authorize the hacks and subsequent leaks, he is certainly intensely pleased by this situation. Alexander Dugin and his friends in the Russian General Staff got everything they wanted, and not only that, they demonstrated the viability of this form of attack. If the goal is destabilization, one is led rather ineluctably towards this exact point of weakness.
The answer to this situation is to destabilize American politics. The voting system we have fairly obviously limits the power of minor parties, and encourages two large parties which are relatively homogenous in aims simply due to the laws of large numbers. So how are we, the electorate, driven to the polls? Wedge issues: global warming, border security, racism. The dissatisfaction with the major parties is very real, as are the underlying worldview differences, so it's not that we would not expect to see a strong conservative and strong liberal party, but these particular political parties have enough skeletons in their closets to sink the USS Enterprise.
The single most effective thing that we could do to improve American politics would be to switch away from "first past the post" voting. I suspect that ranked choice voting would have had Gary Johnson as a second preference on many Clinton ballots, but then again it's hard to see the major parties fielding these candidates if they didn't have the guarantee that people had to vote for one or the other of them. I can't stand Johnson's politics, personally, but I think he made a strong showing, and to the degree that anyone bothered to conduct any polls, I believe he was generally preferred to Trump.
Putin, or anyone else with the inclination, can massively destabilize this country by hacking one of the two entrenched parties. If it can be done, it will be done. The only way to cast a vote against the Establishment is to cast an instant-runoff ballot. If we don't have the ability to make real choices at the polls, both the domestic elites and our foreign enemies will exploit this. And this really should be a pillar of the Libertarian Party platform; for better or worse they are a major anti-establishment force, and although I oppose them with nearly every fiber of my being, I think that they could be successful enough to at least introduce this concept to the wider national dialogue. I also believe that libertarian ideas enjoy far stronger support than is represented in our government. There are downsides to coalition politics and populist movements, but doesn't it make sense to capture more information from voters about what they actually want? In market terms, right now we have two big entrenched regional monopolies, who can stay in business only because the laws prevent meaningful competition (you can supply your own car analogy). I'd really like for this country to all get together and give both major parties the enormous raised middle finger they so richly deserve.