That's a nice collection. You have a lot more of the actual ranger figures, than I do. I'm only recently starting to collect the figures. I mostly collect the mecha. I have most of my Pre-2000 Stuff stored in their boxes and kept away. What I have on display is mostly more recent stuff. Wish I had at least one more shelf. =/.
You talk about villains that kill people. Well, I think they do, they're just killed off screen, or implied. Those explosions the enemy commanders make in the city, or those buildings they blow up gotta kill people somewhere along the line.
The real reason why you see less onscreen death in Sentai than you used to before is that Sentai's audience changed. Parents complained about the violence. They just toned down that sorta thing. If it were back in the air around 7pm then things might be a bit different.
Same thing happened in the Pretty Cure series. The first three series had some very brutal fight scenes.
Cure Windy GOT KICKED IN THE HEAD by Kintolsky. Awesome fight scene.
Parents complained. Things got lighter in tone as things went along.
By Heartcatch now, the enemy commanders are pretty damn lazy.