Now some dickwad comes and tells me "man, that is illegal". k
> I know it's meant to stop idiots from doing work that could endanger them and others
Yes, and it's a lot bigger problem than you might think. You know what you are doing, but 99% of people don't, and they will happily murder the next owner / next occupant through their own malpractice, without even thinking once about it. I've seen professional home builders screw this up and fail inspections, multiple times. It's a real and common risk.
That is _not_ the person I want working on a gas line (which is "plubming") on a house I'm going to buy in the future.
I'm sure you're a special little snowflake that's good at everything, but if you don't feel comfortable getting a permit for permit / license-required work, then... um... maybe you shouldn't be doing it? That's the context for the advice I gave to the parent poster.
Never do anything structural/load-bearing. Avoid touching window-headers/columns, door-headers/columns, that random beam in the middle of your living room, that random pillar that you wish you know what was for, and that really inconvenient wall between your kitchen and your dining room (those are likely "important" points).
Other than that, paint... sheetrock... siding... sheds... trim... cosmetics... run wires... drill (some) holes... attach things to things... it's your house!
I learned the most by watching Income Property and Holmes on Homes.
http://www.diynetwork.com/shows/income-property
https://en.wikipedia.org/wiki/Holmes_on_Homes