Interesting points, but there are multiple plot holes in your narrative.
1) Droids are not "alive." That is THE key here. If you enslave a human for 40 years, you've taken half of their life. A droid can be shut down for 40 years, turned on, and active for another 400 (if they get maintenance).
2) Wiping a droid's memory does not equal "death." Death = death. Since droids are never actually "alive" they cannot "die."
3) AFAIK the "sentience" of droids is never discussed in the main films. I admit I know very little about what canon is in the Star Wars universe at this point.
2024 chatbots can converse at a near-human level. By 2034 I expect a "droid" will be able to converse on a level with C3P0 but will not be sentient.