I think skill degradation can be ok for certain skills, but does need major attention to balancing, as it can make skills that can only be used under specific circumstances impossible to improve if they all degrade at the same pace. For example, doctoring, that one is only usable when someone's sick, needs a surgery or is hurt. When everyone's healthy, it's impossible for a doctor to practice his/her skills. There's no alternative like studying or whatever to keep a specialized skill like that up, that can only be used under the right circumstances.
As for the main idea of having researching have a secondary skill associated with each research project, I do like that idea. That actually creates a reason to have other colonists who are good at both intellectual and some other specific skill actually bother to be assigned a higher priority to research for specific projects. That reduces the temptation to have 1 colonist be "the researcher" and that's all that colonist ever does, all day, every day, until they get crazy good at researching. A mechanic like this would force the player to have to balance out what you research, when, and who does the research.
For skills like doctoring, I'd like to see some items that colonists can use to study. Maybe for doctoring, medical journals/books could be bought from a trader that allow each colonist assigned to doctoring the ability to study it for a finite amount of skill before the item becomes useless for learning, for that colonist. The items could also have a secondary effect that does not exhaust that halts skills decay for a period of time after completing a study task on that item. Each skill could have a similar set of items, such as textbooks, trade magazines and so on that impart skills up to a point and halt skill decay.
So if you're wanting to research how to build those fancy new chairs, for example (a construction research) don't do it while you're in the middle of a major base expansion project, or you'll either tie up your research on a project your other researchers won't be able to do any time soon, or you'll tie up your best builder on a research project right when you need him building stuff.
As for the main idea of having researching have a secondary skill associated with each research project, I do like that idea. That actually creates a reason to have other colonists who are good at both intellectual and some other specific skill actually bother to be assigned a higher priority to research for specific projects. That reduces the temptation to have 1 colonist be "the researcher" and that's all that colonist ever does, all day, every day, until they get crazy good at researching. A mechanic like this would force the player to have to balance out what you research, when, and who does the research.
For skills like doctoring, I'd like to see some items that colonists can use to study. Maybe for doctoring, medical journals/books could be bought from a trader that allow each colonist assigned to doctoring the ability to study it for a finite amount of skill before the item becomes useless for learning, for that colonist. The items could also have a secondary effect that does not exhaust that halts skills decay for a period of time after completing a study task on that item. Each skill could have a similar set of items, such as textbooks, trade magazines and so on that impart skills up to a point and halt skill decay.
So if you're wanting to research how to build those fancy new chairs, for example (a construction research) don't do it while you're in the middle of a major base expansion project, or you'll either tie up your research on a project your other researchers won't be able to do any time soon, or you'll tie up your best builder on a research project right when you need him building stuff.