The color pallete of the base still does have that level of grunginess and barreness, it's just an actual literal layer of grunge overtop the original design of the facility instead of being baked into the facility's design. It provides a more meaningful reason to clean the base other than out of habit between signals, rewarding a player with interesting murals and a fun look into what the facility was like decades prior. Not to mention that the game prior to the 0.9 builds still incentivized the player to make the facility colorful and comfortable with a variety of decorations, lights, building tools, appliances, collectible plushies and even the ability to add your own models and videos to the game world.
Also, if you don't like the new design, you can always just play the older versions. There's nothing stopping you from doing so.