Exactamundo!
Don't know the full scoop on how it's implemented, but either way it's a start. Inconvenience could piss people off enough that they just stick with the feature and learn it. Or more likely, quit and leave a nasty review.
Restriction is part of the challenge in an RPG. It plays into the overall balance of the game, short-term and long-term.
Remove restrictions and RPGs would have unlimited skill points to spend, unlimited money, unlimited carry weight, unlimited rare herbs to pick and then any interesting "game" would cease to exist. It would be like chess altered so every piece could move like the queen.
For an example of a type of mechanic I'd consider similar, Lords of Xulima has a food mechanic where you had to buy food so your party could survive. Food was expensive, which restricted your spending of money and played into the overall balance of the game considerably. You had to make choices on how much food to buy, should I buy extra food for a long trip? Or a better shield for my Paladin? If you combine it with the Ironman feature, which restricted saving to town-only, all of a sudden you had an RPG like you'd dream of as a child. You're on a journey when you leave town, so you better be well-stocked! And while you're out there, you better work to survive!
This feature also allowed them to put food-related skills in the game, too, so you could spend skill points for a character to pick more herbs/food, and then you would have more money to better equip your characters. It is a trade-off, and a consideration had to be made when developing your character, as well as the overall party synergy, and how you spend your skill points and also your limited money. Developing the characters this way also differentiates characters, gives them personality through stat development and creates interesting decisions to make when leveling up. This is what a great RPG does, it gives you choice & consequence, not only in story, but also in
gameplay.
Back to Kingdom Come. If you get drunk when consuming booze, that means you can't simply save-spam every 5 steps. This means that there is added tension. It means you will have to be more careful about exploration. The further you "go out" into the dangerous area, the more risk you will face. This is exciting in an RPG! What is a game without risk? A good developer will also reward the risk well. Maybe the longer you go without saving, the higher XP multiplier you get. Or the chance of encountering a rare encounter gets higher. There are lots of ways to do interesting things with these sorts of mechanics.
They could even have a "drink like a fish" perk where you can consume a bit more alcohol before getting sick. You may say, "So what? It's a small thing, why even have drunk quicksaves to begin with?", blah blah. But to get that perk it means you had to spend a point on it, which means you had the choice to get a different perk instead, knowing that the drinking perk would be very helpful as well. C&C gameplay. Different ways to be creative in how you build your character.
I know I'm in the minority with this (trust me, I know) and expect the usual backlash about these opinions (because most gamers just don't like to be challenged at all in games.) I enjoy a decent challenge in RPGs which is why I stick to mostly niche titles.