@Cheesecake Stock-parts, in principle, can not to be overpowered for stock. They are the stock as it is. They form an overall balance of characteristics, which the developers control, and if some property of a part falls out of the characteristics, it is compensated for by another property. This is how the general technical level of all parts of the KSP is formed and allows them to be harmoniously used in one game, complementing (but not replacing) each other.
A rocket similar to Saturn 5 is not required to do the same as Saturn 5, since this is not Earth, but Kerbin. It has its own rules, and the achievement of many goals is simplified to expand the circle of players and increase the fun. But the stock balance creates a common field of rules for all, in which the mechanics and logic of the game work most reliably.
At the origins of KSP modding, mods often appeared that had characteristics better than stock ones, and made them unnecessary, but later the modding community recognized this as an unworthy behavior, and most of the surviving mods either have the characteristics of parts according to the stock balance (supplementing the stock set, for example, Missing History), or expanding the stock in areas that it does not cover - historical vehicles, unique parts, components for large orbital stations, future technologies beyond the stock tech tree or means that significantly change gameplay - life support, new resources, colonies, etc. Mods with overpowered parts make it easier to achieve the goals of the game, and in this they come close to cheats, destroying the stock gameplay. Anyway, there are people who like the "easy way", cheats, etc., so they like these mods. But the use of simplifying mods for JNSQ or more complex planetpacks is not entirely clear to me - after all, they are chosen to complicate the game in comparison with the stock, so why simplify the game? Complicate to simplify later ??
Well's mods have always been distinguished by the great beauty of its details and good functionality, and the stock balance for other mods was mostly respected. Luciole is a rare exception, well, let there be at least one, why not? But I played enough of it very quickly, and I see no reason to include it in my career. Imho if a player wants to go through the game in a more difficult way, into JNSQ, he will go through it even with stock parts only, or add life support etc..