You can place pre-made asset and be done with it or you could spend some time to make it more real and pleasant.
I get what you say, but disagree with this being "a detail". Of course, it's not obvious when looking at the average game on the adult gaming scene, but doing this is the base.
Take "Ashley Boutique" by example, that is probably the most used clothing store. It don't need advanced knowledge, nor really more than a hour, two if you want to fully rearrange it, to turn it into something more personal.
It come with an empty version where you place the mannequins and clothes. Changing the name of the store take 2 minutes to make a beautiful "My store" image with transparency into Gimp and use it in place of the current texture for the shop window. While changing the color of the walls don't really need more time.
It would still be the same assets, and it would probably looks a bit familiar, but in the same time it would have that unique touch you're asking for.
But yeah, I agree that too many devs don't do this... And the worse is that it make players think that they are all as lazy. Then, when a dev need one week more, because (s)he struggle to make some assets looks the way (s)he want, not only near to no one will notice the efforts, but (s)he'll also be called "milker".
But, once again, this isn't a detail, it's the base.
It's the first thing that a dev (or his/her artist) should do, taking ownership, figuratively speaking, of the assets. Looking what can be removed or even just moved, sometimes mixing two assets, using the shelf from one in the walls of the other by example, and so on. Not that it need to be done with every single assets, some are perfect as it, but it's the assets that should adjust to the story, not the opposite.
I mean, how many fucking games have the cash register show a sum that isn't what the seller is saying ? And how many clocks display the same hour whatever the scene ? How changing this can not be the base ? At worse you don't know how to do the exact same display, then just use a full black texture and make someone tell that it's broken, it will looks less stupid.
Edit:
Sure they have "details" but they nearly always lack any sort of personalization.
It's Daz Studio simplicity, and large assets catalogue, counter part.
Assets are good right from the starts, and once you placed your characters and posed them, you can click on "render" to get something good enough... So, people don't really looks further, and miss the whole power behind.
All this being coupled with...
Character is young? Let's use this generic gamer-bedroom that looks like the owner spend thousends of [insert your currency] in its setup without even being a gamer or anime/pop-culture fan.
A total lack of imagination.
If dev can't achieve to give a personality to his characters, why would he achieve to give one to the place he live ?
They browse Daz ship, use "girl room" as criteria, and will use the one that they love the most, period.
And the rest of the house? Don't touch anything, don't move anything, don't leave anything lying around, the real estate agent could come by at any moment.
To be fair, this isn't something easy to do. There's tons of clutter assets, but to turn a room into a living place need to use a tenth of them, hoping that they'll more or less marry harmoniously. But sometimes it don't need much. Luna's room in
The DeLuca Family just need need few guns on a table to take life.
And don't you dare to replace any of the sample pictures of the picture frames that came with the product!
While this is probably the easiest element to tweak. Click on the surface, go to the surface panel, look at the file used as base color (it's generally where you'll find the main texture), then open it in Gimp/Photoshop/whatever, and replace the picture. Yet this is only when the picture don't have its own personal texture, what is even easier to change...
And... grumpy me is back, I'm sure you all missed him.