Earlier quoted context omitted.
Most Android developers I know (and even some iOS developers) consider the Intent system one of Android's diamonds in the rough. Could you perhaps explain how you would've designed it?
The concept may be a diamond in the rough i.e. co-operative multi-tasking. The implementation, not so much.
Intents are great in concept and they work out well for users, but the interface/API for using them to do anything can quickly become painful if you go even a step off the beaten path of "perform this operation with these parameters".
A common recurring theme with Android (and this applies to all the major bits -- Activities, Fragments, Services, etc) is that you'll easily hang yourself if you don't have a really clear picture of how they actually work but you attempt to use them. Android almost completely fails, IMO, when it comes to the concept of "keep the easy things easy". There's a huge upfront cost to understanding the major components before you can start really using them at all safely, in my experience. As a bare minimum, if you don't have an intimate understanding of the Activity and Fragment lifecycles and a full understanding of what needs to be on the UI thread when (and when different callbacks from the OS are/aren't on the UI thread) you are likely to create a terrible mess of an app that kinda sorta works on most devices, usually, but is broken in some fundamental ways you aren't aware of.
I don't personally know any day to day Android developers who haven't spent a considerable amount of time in the AOSP code trying to figure out exactly how some of these systems work because failing to understand them internally combined with lack of any sort of clear direction from the platform team (extremely open case of there being more than one way to do anything, which makes authoritative answers to the question "How should I do this?" nearly impossible without a long list of caveats) is the path to writing Android code which mostly works but has some fundamental mismatches with the operating system and becomes a complete mess to maintain.