All the following is IMHO, of course, and I want to emphasize that point.
Traveller is my favorite RPG, regardless of which edition one is talking about.
What all RPGs need, but especially Traveller, is a modular approach to the rules. This is based on the S.O.L.I.D. principles of software design.
1) There needs to be a very, very, simple version of the rules that players and referee can just sit down and play with a minimum of preparation. The goal of this version is to allow the players and referee to concentrate on ROLE playing and story telling, with little need to be concerned with record keeping and other details. I would imagine something like a maximum of 20 pages of rules, with a maximum of 4 tables, for this simple version.
2) All other rules are provided as small add on mini rules modules, with each one being self contained. I would expect such modules to have at most 5 pages of rules and one chart.
3) ALL such rules modules need to be OPTIONAL, so that the Referee can choose which ones to use or not use, and can therefore adjust the complexity and detail of his game to fit himself and his players.
A system like this will have enormous advantages over any existing fair I know of.
a) It makes designing and testing easier, resulting in fewer errors and contradictions, and thus less errata.
b) It will provide a very friendly way to introduce new players to the game, by starting them with the simple game and then adding optional rules one at a time.
c) It will allow the Referee to tailor his game's complexity and level of detail easily.
I even think that Traveller might not be that difficult to fit into the above scheme.
1) Simplified character generation becomes the base game. One plays a character's whole life out using the character generation rules, which need to include a simple 'event' system similar to that in Mongoose Traveller chargen. Naturally some means would be needed to allow multiple players to play simultaneously.
2) Additional rules modules either add more details to the base game mechanics (such as new career options etc.) or they add more detail to the events, giving the characters more options. The events in effect become adventures, which can be as detailed, or not, as the players and ref desire.
This probably mean that the standard idea of the characters getting together after completing their pre-history and entering a life of adventure separate from the chargen is discarded. I have no problem with that approach, but I would like to know what others think.