Looking at this thread again led me to take a look at the 1977 Edition of Classic and the 1981 Edition of Classic again see how skills are handled. Not surprisingly, there are some differences.
1977 LBB
In all of the years working with Traveller, I totally missed that comment on fractional expertise levels from gradual acquisition of skill levels during the course of the game. Effectively, this allows for experience gain in the game, so that your player-character is not permanently locked at their current skill levels. It would seem to be reasonable to apply this to all of the various skills, and not just weapons, allowing for gradual skill gain during the course of a campaign.
1981 LBB
The Jack-of-all-Trades rule is another that I have missed, but it definitely makes the Jack-of-all-Trades skill a lot more valuable. I would have to think about it applying to every skill, but maybe groups of skill would be more applicable.
Personally, I like the idea of half-skill levels better than Skill Level-0 indicating some familiarity with the skill involved.
Lastly, although this has been mentioned in other threads, this quote is also from the 1981 Edition of the LBBs.