I agree that that group is historically underrated. Cowens + Havlicek + JoJo was a heck of a core.
I think the 70s Celts aren't considered to be among the "great teams" of the franchise because they didn't have the same success that other Cs teams did up until that point. They missed the playoffs four times in the decade, and "only" made it to the Finals twice. Compared to the 60s and 80s teams, they just fall short in terms of their legacy.
You're right, though: that '73 team holds the franchise record for wins (68). But for Havlicek's injury, they probably win 3 out of 4 titles.
Roy - the playoff absences were after the team was decimated by injury, age and free agency losses - 78 & 79 were as bad as any dark period of Celts history and '70 - '71 were rebuilding. - i don't count those years against that championship group. to my mind, 1972 - 1977 didn't equal the 60's dynasty, but it rates near the 1980's run and exceeds the current group.
they were my favorite teams as well - Cowens will always be my all-time Celtic - i see him as one of the four cornerstones of Celtics history along with Russell, Bird and Garnett. KG needs another banner. Havlicek, McHale, Heinsohn, Max, Pierce & Cousy all essential lieutenants.