The irony is that Samsung (and many Android phones) have much larger batteries than the iPhone, yet have to resort to power saving measures to get better battery life. Without it, their battery life is atrocious. I have used many Android phones, including the various Nexus', HTC One, Xperia phones, Samsung phones and tablets, and Motorola. The only phone that can probably rival the iPhone in power management without resorting to "battery saver" or "stamina" mode is probably the Moto X.
Many of those battery saving modes are misleading anyway. They usually do it by disabling background cellular data, which defeats the point of having a smartphone. Then you end up having to white list apps and whatnot. The lay user doesn't have time nor the knowledge to micro manage those. The OS and phone should be good enough by itself. Samsung should actually get rid of its bloatware, and they probably won't need the battery saving mode.
I have the One and it's not atrocious in the least. And I know from several reviews on other high end android phones, their batteries get good ratings with all day moderate use without resorting to power saving. And my power save does not disable cell data. I've never had to manage the save mode but I've looked at it and it's not complicated to manage either. When I do need to keep my phone alive because there's only a few percent remaining, I easily put it into power save and manually turn off data just like I did when I had iphone. You act like having options about which apps to keep running and manage is a bad thing. It doesn't take a rocket scientist nor weeks to figure out how to manage apps on android. The majority can easily check boxes.