I can think of another pretty big RPG out there where you don’t really improve: Fate. In Fate Core you characters change over time, but it’s not an improvement as much as it’s moving your various aspects and skills and stunts around to reflect your character changing focus in life rather than mechanically becoming any better.

Personally though I like the option of advancement at least, and there are many such optional systems out there for Traveller as well. That said I’ve never minded that Traveller doesn’t have an experience system or anything like it because of… well, the things you listed above.

There are some exceptions though: I think characters should be able to change in stats in Traveller, to some extent. Social Status is the obvious big one here, as a character who is for example knighted in the Imperium during the course of the game definitely should get a marked increase in the stat, but given that Traveller often involves timeskips of several weeks at a time due to jump travel the same could be said for Strength for example, as a month of working out with nothing else to do on board a ship definitely should allow for that stat to improve, if only a little bit. So far I’ve just handled these sort of things ad-hoc, and it’s been fine, but it’s something to take into consideration anyway.

Traveller is Star Trek. It’s Firefly. It’s The Expanse. No leveling up. Just stories told.

In theory, GURPS characters improve. In practice, many games have point accrual happen so slowly that they basically don’t. And then there’s Call of Cthulhu and Delta Green, which are races to the grave.

I think Traveller is amazing. It makes a lot of sense as skills take a long time to learn and practice. I would think it’s something like EVE Online, it takes days and months to gain skills. It’s not like fantasy ones where you kill an enemy and you suddenly learned a spell or a skill out of nowhere through experience points.

I turned 40 in October and in the past year-and-a-half, I “leveled up” more than the previous10 years combined. Huge growth. Not a brag, just pointing out that in a game without character advancement, this kind of personal growth isn’t possible.

That said, I like Skill-based games where advancement is more realistic and where you start as a “pro” instead of a wet-behind-the-ears punk.

When we played Traveller back in the very early 1980s it always seemed weird that we didn’t “advance” like we did in D&D, but honestly we didn’t think too much about it. We had a great time anyway. Also, great blog!

Classic Traveller DOES have character improvement, it’s just not easy and it’s slow. Look in Book 2… You choose two skills to practice, and then make an 8+ roll with no DMs, if you succeed, you immediately get +1 in those two skills (you must already have the two skills at least at level 0 – if combat skills, they must be a gun and a blade). After 4 years, if you were improving from level-0 to level-1, the increase becomes permanent, otherwise you must spend another 4 years (with another 8+ roll) to make them permanent.

Quick point of clarification on the Hero’s Journey: that is a journey for common people, not superheroes. Tough life choices, insurmountable odds, turning points, acting above and beyond, facing fears and conflict rather than running away, etc.
Also, I agree with Robert above, I would think that if you’re playing a chara ter through a several year (in-game time) campaign(s), that each conclusion should award experience that translates in to skills. Ffilz mentioned possible growth mechanics for CT and I think Mongoose 2e has something similar.
But, I could see rolling on the Life Events tables, or GM/Player negotiatied skill advancement based on adventure “learnings” as a viable growth mechanic.
I’m about to GM my first game and I think I’ll hack this aging/advancement skill thing a bit. Including the option to port skill points from one of the physical skills (Str, Dex, End) to one of the non physical skills (Int, Edu, Soc) every 4 years… or so.