You're cherry-picking two cases of worst-case scenarios, one of which wasn't even really a democracy.
The Soviet vs. Imperial Russia example was to show that the general argument applies across all forms of government.
1: There continue to be many attempts to disenfranchise voters in many states through various means. Statistically the number of attempts at voter fraud are non-existent compared to the number of people whose legal votes are denied, but it makes better show to pretend otherwise.
Most of those efforts are simply symptoms of our use of districts. A simple shift to a proportional representation system chosen across the entire polity would eliminate the most pernicious form which is gerrymandering.
In actuality, most of what is called efforts to disenfranchise are actually efforts to add integrity to the system such as voter ID laws. The idea that you should be allowed to wield any political power without being positively identified as a citizen eligible to wield it is utterly insane, but par for the course for certain types of ideologues (don't know if that applies to you personally)
2: The US tends to fail on both the systemic and systematic levels. As a society we're not providing enough support for the education system, and when it comes to elections allow ourselves to fall prey to the spectacle of network news soundbites and commercial advertising too easily, rather than really educating ourselves about the people and issues involved.
Funding is certainly not where we're failing. Many of the worst districts are funded with the same devil-may-care attitude toward how much we're spending that is used on the military at the national level. The problem is that our educational system is structurally flawed in ways that are politically impossible to fix. It's a problem of culture and political will to address the culture.
4 & 5: These two are rather tied up together, and contribute greatly to the issues with #3. A first past the goalposts election system almost inevitable leads to a two party system, in which the voters grudgingly and unenthusiastically vote for the (perceived) lesser of two evils and in which the winner feels only a vague sense of responsibility to those who elected them. (If you piss off your constituents what are they going to do? Vote for the greater evil instead of the lesser one? Not likely!)
It also doesn't help the situation that politicians know that the majority of voters are low-information voters. Point #1 greatly exacerbates that. The easiest way for politicians to destroy the influence of the more informed voters is to drown them in a sea of low-information voters who are the sort of people that are congenitally more interested in their own immediate creature needs than the public weal.
Like it or not, most low information voters are not that way because there's an informed citizen waiting for an excuse to burst forth from them. They are simple people who have simple needs and expectations. A lot of them are even smart people. Some of the dumbest arguments I've had on politics were with badly informed people with high IQs.
Expanding to a more democratic system provides a great deal of cover for the political class because democracy feels like we have power, feels like "we chose this." If we had a monarchy like Imperial Germany, the King would have feared a violent revolution over some of the scandals that have come out in the last 20 years because the public couldn't just say "we'll vote the King out." Consequently, I think a less democratic system would have likely chosen a more moderate and accountable course of action because the lack of an illusion of control would have channeled the public outrage directly at them.