I understand whay you mean, man... i feel this way too... it seems our brain "learned" how is to be high, and now it behaves "highly" even when we're sober... or talking in a more "serious" way... it seems we conditioned our perception and our senses to percieve the world the way we do when high. Cause when were high we percieve things that we dont when were sober, or we percieve things with much more detail than when sober, like the colors, the music, the taste, etc... then after years of working in this "high" mode, our brains learned to percieve the world this way, to notice subtle details in the music, to see the colors more brightly, to feel more relaxed, etc...
I think it also explains a certain kind of tolerance (cause not all the tolerances are the same)... cause as our brain become used to work in the "high" mode, smoking does not change it so much, as it already was in the high mode, and thats why we feel that smoking does not make us as high as before... i noticed it long ago... when i was a newbie, i could say that i was high looking at the colors... they seemed pretty intense... now, when im high, (unless i be ridiculously blazed) the colors seems almost equal what they were before i smoke... the difference is very small... and it is true for almost every effect of smoking.
I also dont complain very much about this, cause it enables me to stay without smoking without feel any need to do it... but its a bit sad because the highs are not what they used to be anymore...