True, but with trapdoors already serving the purpose for "thin walls" to a limited extent, it makes you wonder about the real reason why they're ignoring the requests for vertical slabs, which would be more accurately called "wooden walls" if wood type.
with spruce trapdoors you can make a pseudo wooden wall, boardwalks, bridges or a thin outer skin for your huts that has a different texture compared to most other wood in the game. It's not intended for that purpose but it works just as well.
It's wasted potential, there's so many options that could be added for builds but unfortunately unless you use mods, you may never have them.
I think what makes minecraft fun is that its simple and allows for a large amount of creativity. Its the balance of those 2 things between simplicity and complexity that makes this game shine. The order of it too! This game does an excellent job at keeping things simple at the start of the game, and allowing the player to progress in complexity at their own pace.
For example, you arent forced to turn the difficulty to hard first to start your new world for hunting trophies/achievements, you can actually start off on peaceful first, gear up or build your base up, then switch to easy, normal, or hard to get all your trophies! You also dont have redstone to make a door, stairs to make steps, or enchanted armor to fight the enderdragon, you get to decided how complex you want your experience to be,and thats whats really fun!
So like, i 100% agree with you ith the idea that verticle slabs would do nothing to harm the game. Anyone who disagrees i'd argue is likely trapped in a mixture of fear and a lack of understanding of what actually makes the game special, where fear is the weed and the lack of understandimg is its roots.
If there was anything i could tell to the developers, is to think about what makes the game special again. Its not limitations, its about the progression of removing those limitations. Its going from a dirt house to a mansion, its going from a simple lever and iron door to a automatic sugarcane farm (or a computer lol), its going from leather armor to enchanted netherite armor, and starting with nothing to slaying a dragon!!
Its that slow progression to all of those more complex things that makes players get sucked in and fall so in love with the game.
Verticle slabs fit very well into all of that