why do we use systemd?

[Heinz Diehl]

On 05.07.2014, Patrick O'Callaghan wrote: 

> It allows the various components to have specific dependencies so they
> can start as soon as everything is in place. Older mechanisms such as
> the traditional System V init scripts were much more limited and could
> only do this with very ad hoc and buggy per-service tests, so they
> mostly didn't.

Do we need that? I mean, what's the advantage of having a speedier
startup wrt the introduction of massive complexity? Do we need the
saved seconds for something useful? How much time do we actually use 
to manage/struggle with systemd in comparison to a potentially slower 
but more mature and less complex system?

Just curious..