Lets face it, sysV init is complicated. Well, the theory behind the old linear start from init script 00 and move to init script 99 isn't, but the modern implementations and the scripts themselves are complicated. I mean you're doing dependency checking and a whole bunch of other things in bash scripts. Compare that to a systemd service file, which is overall nice and readable. So, part of it is factoring out the logic from the variables. The other big thing is bash and the tools used by init scripts are like using a sledgehammer to tap in a finishing nail.
I'm not going to say that systemd is perfect. I like the "unix" way which is to use small units that do one thing well instead of anything. That's part of the reason I see bash init scripts as too much for the job. Unfortunately, the systemd authors look like they want to throw in everything but the kitchen sink. Well, everything that they can't just port to kernel space that is. But that's the thing, Linux is a Monolithic kernel. Like it or not, the "Linux" way is to have one uber optimized thing with modules to handle everything.
In the end, I just really like the ease of use of service files. Oh, and the stupidly fast boot time on my laptop is really nice. People who say boot times don't matter aren't living in the real world.