Yes that is essentially what decay is. Reverb depth and time. For instance, on one of my demo song (I am I from Queensryche - Promise Land album) the snare drum has a deeper, longer and clearer sound on the T1s than on the D2K. I can hear and feel the depth of the sound after the initial hit from the drum stick, that's the way the engineer recorded the sound but it only comes through on headphones or speakers capable of resolving that detail. It just makes the overall sound experience richer when details far in the background are actually heard, even if faint, they are there and add to the enjoyement.
SO short decay means more detailed and defined sound in general.
Tank you :-)