"The earlier and the greater in level the first room reflections are, the worse they are. This aspect of sound perception is controversial. Some believe that all reflections are good because they increase the listeners feeling of space – they increase the spaciousness of the sound.
Presumably there are caveats involved such as the size of the room/listening distance etc.
And also what exactly one means by "spaciousness."
I take that term to mean the sense of the size of the space, and spacing between images - e.g. the more "spacious" presentation will sound like you are listening in to a bigger space, with perhaps even more distance between the images.
In my own room (13' by 15' with a wide opening to a hall on one side, and plenty of flexible room treatment), I have generally found that moving closer to the speakers, which also means more direct sound less reflections, actually increases the sense of image size and spaciousness. It's like entering the acoustic of the recording.
The more room reflections I add, by either moving the seating position further from the speakers and/or allowing more reflections of the side/back walls, I wouldn't say the sound becomes more "spacious" in terms of sounding bigger. But it does tend to get a bit more "airy" in the sense that
the acoustics of the recording seem less "recorded" or less like one is viewing a circumscribed different acoustic happening between the speakers. Rather, the merging of the recorded acoustic with the room reflections "merges" the sound with the sound of the room, so it has a sort of airy "could be happening IN THIS ROOM sensation. Which can be more realistic given certain recordings.
But if enough room acoustics are added in, the sound, for instance of an orchestra, doesn't sound 'more spacious' as if in a bigger hall, but rather it can seem a bit smaller, like the orchestra is being fitted in to my smaller room.
That's why, as I've mentioned before, when I play with modifying listener distance/room reflections, I try to dial in just enough room reflection to add a bit more believable sense of "air" and liveliness, while not having my room reflections dominate the recorded acoustic. When I get it right, the sensation is in fact of an acoustic that has opened up in a bigger fashion, the sense that I'm "in" the acoustics of the recording so an orchestral recording can sound surprisingly convincing like I'm there, rather than listening to a recording.