Bob, I salute you for having the guts to ask a question that, probably, many pipers have had when starting out. I started reading this thread fully expecting to see flames in reply, and have been pleasantly surprised to see none so far (knock on wood). So, maybe your reaction isn’t too unusual.
Before I could play even a note on the pipes, I’d listen to recordings by the likes of Seamus Ennis, Willie Clancy, Altan, and Matt Molloy, thinking “Ah, that’s the stuff! I want to play like that.” So I got a practice set, dove into the Clarke book, and started taking lessons. And sure enough, that was the style and sensibility my teacher focused on: never playing things exactly the same twice through, always making room for interesting ornamentation, never sacrificing musicianship for tempo, etc.
Then, I started going to Great Northern Irish Piping Club meetings, and life got even more interesting: I was exposed to loads of good tunes I wanted to learn, and realized I needed to embrace metronome work (musical ideals notwithstanding).
But the first time I sat in a mixed pub session, I was baffled: almost entirely it was reels played at a zillion beats per minute, always the same every time through, all blending together in a thick reely mush. [yawn]
Of course, I was aware I didn’t yet know nearly enough repertoire, and couldn’t quite play reels at dance tempo. So I dutifully sat and listened for most of the session, joining maybe two tunes, telling myself how humbling and virtuous it was to sit and listen for once.
But I was bored! That session was nowhere near as musically compelling as any of my ITM CDs. No pub session I’ve played in yet has been, even now that I’ve got more repertoire and speed.
As Geoff et al have said, playing in pub sessions just isn’t a spectator sport; it’s background music for dancing minus the dancing. Fun for players who know & like each other and share enough tunes in common, but that’s about as far as it goes.
Now, pipers’ sessions, on the other hand, are ten kinds of cool. House sessions are a blast. And house sessions with lots of pipers rock very hard indeed. 
Just my own, very pronounced, opinions,
Mick
P.S. Needless to say, much depends on the people. The “family sessions” held at St. Paul’s Center for Irish Music are really pretty cool: varied repertoire, human-friendly tempi, and a welcoming group of people. Session playing is, first and foremost, a social event.