^ While I agree with the "just because," I must counter because I have done "long" intros and even outros before.
Now, this is just my opinion and I will use the pronoun you (although I don't mean you specifically), but I do think that you have a short attention span.
There's a song I'm thinking of and I don't know if it's by Queen or Kiss, but I think the intro is long with purpose, but I don't think the outro is truncated to "make up the difference"
As it pertains to me, the "unique" of Blossoms (imo) is "just right" which is also partly at the beginning and serves as the end because that is the part I wanted to have more emphasis. This is because this part is what makes this song different - not the arrangement of what was already established.
I think when the ingredients are shown, it's sends a signal that it'll be something laborious which it's not if the listener like the composer divides it into sections.
5+ minutes all at once could seem intimidating to some; however, if it's structured such that the listener is able to section it off then it's not as long as it seems. Hopefully, you already did this when you wrote the song or lyrics.
30 minutes is a long time for a child; however, what do they do? They ask you what time it is every 5 minutes, They broke up that block of time.
A sixteen bar chorus is too long for something at a moderate tempo; so split this into eight bars. Pop/R&B songs do this with split verses/choruses Hiphop or Rap usually sees 16 bars verses; however, these can also be split into 8 bars (32 beats) or 4 bars (16 beats) a piece.
I've got split-bridges. At what point do they split? That's for me to know and the listener to find out as well as when does the intro stop and the song start? I don't think said creators make it difficult to figure out on purpose - f they do so at all.
But I agree with you on the creative and technical aspect and this goes for entire songs; however, you shouldn't feel it's necessarily to get too technical or creative as to think you'll keep a listener if you do because like the while one hand, one can play Chopin's Minute Waltz in half the time; the guy who can play it and may need to play it at half-speed may have more ears gravitate towards him.
Showcasing is different than showing off. While both are legit terms, people do confuse them sometimes, although it is easy to spot the difference and that might be why. (This is of course subjective), but there is a clear difference.
Having said this, long intros/outros or songs in general do have their purpose and it's not always to show-off. It may be just because that what it is. ie: you with long-winded posts which I can clearly relate to.
However, I don't doubt most who know our posting style know we aren't about showing off. We're just passionate about our craft. It's when you start boasting about it is when it becomes showing off and no one likes folks who boasts.
[Perhaps we should truncate these before we
are accused of showing off! (!)]