Topics

Research direction should be more vague, unless the researcher has high enough research skill, or unless you have a colonist with a high-enough related skill to think of the idea. Or maybe you can find "lost technology manual" items to reveal a research topic to you, and maybe boost research on that particular topic.

If none of your colonists "think of an idea" then you can still research them, but you have to do "exploratory research" in one of the larger categories to discover the idea first.

Of course you'd probably want to rebalance how long it takes to research each topic.

For example, just using existing research options, it could be like:

Food Improvements
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- Hydroponics          (thought of by colonists with 9 growing)
- Nutrient resynthesis    (thought of by colonists with 6 cooking, 5 research)
- Fertilizer pump       (thought of by colonists with 5 growing, 5 construction)

Social
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- Crematorium         (thought of by colonists with 6 social, 3 construction)
- Cryptosleep Caskets      (thought of by colonists with 9 research)
- Carpet Making         (thought of by colonists with 5 construction, 4 social)
- Colored Lights         (thought of by colonists with 6 research, 5 social)

Economy
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- Geothermal Power      (thought of by colonists with 5 construction, 5 mining, 6 research)
- Pneumatic Picks      (thought of by colonists with 8 mining)
- Electric Smelting      (thought of by colonists with 8 craftsmanship)
- Machining         (thought of by colonists with 7 craftsmanship, 8 research)
- Tailoring            (thought of by colonists with 7 craftsmanship)

Medical/Military
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- Hospital Beds         (thought of by colonists with 7 Medical)
- Gun Turret Cooling      (thought of by colonists with 6 shooting, 5 research)
- Mortars            (thought of by colonists with 8 shooting)

etc.

Hiding research options like this will also make it possible to add in more powerful options with less chance of unbalancing the game, since you can control how likely or how quickly a player will be able to obtain them.

This would mostly be a cosmetic change in the game.

Add a number of icons that can be overlaid on the Overview or otherwise on any given colonist, to allow players to identify quickly which role they have decided they want that colonist to play, without reevaluating their skills. Especially with higher populations this will be very useful, with a high payoff for implementation difficulty.

Icons could be simple things like a gun, a leaf, a hammer, a flexing-bicep-arm, a speech bubble, a shovel, a frying pan, a chef's hat, a graduation-cap with tassel, a bow-and-arrow, a butcher's knife, a police badge, a red cross, etc.

Just add several colorings of each of the above and you've got a ton of icons without much extra work. I'd be willing to do artwork for it, even, but I don't know how to do vector artwork .