I do not understand what you mean with "...but still a system run with voting and by only a few."
When 17 out of 20 voters come out to vote, that is not even close to saying "only a few."
Plus, you are aware that all Swedes are automatically registered, right? So, there is no discriminating administrative layer preventing anyone from voting like we have here in the USA. The eligible voters in Sweden are ALL registered. Seventeen out of 20 come out to vote. No one is holding back; they own their own government.
Proportional voting is an excellent way to have a population's wishes be expressed by their representatives because the voters send any representative packing when they don't walk the line the voters expect them to walk.
In Europe, the representatives are five to ten years younger than in the USA, because the voters can send the representatives packing, and they do it without any personal consideration. It's politics after all.
Direct democracy may come close to giving folks the feeling they are in control, but the smarter solutions are found when folks have professional representatives doing the political work for them.
A voting population picking from two options is never smarter than having coalition parties figure out how to serve their own supporters best.
Remember, they have representatives in Sweden. We do not have representatives here. We only have winners representing the majority of the voters who had to pick between winner and runner-up. The Swedes are fully empowered; we are not.
--
We are not going to get proportional voting for our Federal elections, so there will be no direct improvement in the diversity at that level.
Yet, once we have proportional voting in place for cities, counties and states, then the diversity will be expressed directly into these representatives, and from this more-diverse political body there will be a greater trickle up to the Federal level than what we have today.
Remember, New Zealand changed its voting system in 1996 and with one single election, the number of females jumped from 21% to 30.8% (now, the females are actually one representative ahead of the males).
When the system is pure, we end up with a pure representative body. In the USA, we can only get that for local and state elections, but it will be worth the time getting that put in place.