One of the things I find about convoluted rule sets is the idea that there needs to be a mechanisms to cover every contingency, whether or not that contingency comes into play. Just in case the characters are disarmed, and fighting over who gets better hold of the jade statue, let's include grapping rules. On the off chance that characters moght need to sneak in somewhere, avoiding the attention of guards, let's include some dramatic stealth rules...
...all these rules need to go into the main book...
...oops, we've blown our page count. Let's keep the common rules, then throw the uncommon rules into a "player's guide", and the rare rules into a "GM/DM/Referee's guide".
We've all seen systems like that. It's common in "traditional" games. I know that my description is fairly glib, and designs teams are probably more likely to think that their rule systems are becoming more versatile, and thus more likely to be used in a variety of game styles and story types, when they add those extra rule mechanisms to the system ecology.
Hence I want to do something different.
It was always the intention in both the original incarnation of "Tales" and the first published version of "The Eighth Sea", to create a fairly streamlined core system that would roughly handle just about anything... it was similarly the intention to create a series of specific stories, each of which included a specific new rule that facilitated the type of actions associated with this specific story. I started doing this a bit with "FUBAR", and it seemed to work. It also seemed to work with "Ghost City Raiders"...I just need to stick to it.
The current "Tales" rewrite, with pocketmod core rules and pocketmod scenario guides, seems a good fit for this style of modular rules. The whole idea is to generate a simple set if rules that anyone could quickly get the hang of, with the depth you need, only when it's needed.