Guess I am in the minority here AND maybe I am hard to please

To answer the question (nice post by the way) YES, I do have a bitter taste in my mouth.
The Celtics SHOULD have won more than one NBA title during the KG era and they didn't.
I also think excuses are being made for the shortcomings in their quest for banner 18 from 2009-2013. Here some reasons why I think we should won another NBA title, came up short and it did not have anything to do with injuries (which by the way, are part of the game.)
1.)
During the 2008-09 season, I feel like Danny took his eye of the ball. REMEMBER, going into the season we lost James Posey and PJ Brown (and to a smaller extent, Sam Cassell) who played a pretty big role in the 08 title run.
Danny really didn't acquire anyone to replace them, thus we had a weaker bench. In fact, if I remember, the only players Ainge acquired for the 2008-09 season were Patrick O'Bryant and Stephon Marbury.
O'Bryant had bust written all over him (and was then subsequently traded) and Marbury was clearly done as well.
Even with KG's injury, DA should've gone out and acquired another body or two for a repeat run and he didn't.
I remember at the time, after KG's injury, the prevailing thought was "oh KG will only miss 2-3 weeks, and be back plenty strong for the playoffs. The team will be fine." Well, that wasn't the case. AND by the way, that was BEFORE the trade deadline, only further emphasizing Ainge's fault in not being proactive to help provide the team with enough healthy bodies for the stretch run.
2.)
The 2009-10 season. Remember, this was the year where the Celts were 23-5 by Christmas and then 27-27 the rest of the way. Quite frankly, the Celts got lazy in the 2nd half of the season. They were good enough where they were able to get away with it and crush Miami, Cleveland and Orlando in the playoffs.
But against the Lakers in the finals, the basketball gods were not kind and the Celts complaceny from the regular season caught up with them in the finals.
The Lakers had home court advantage that year and they earned it because they were a higher seed.
Had the Celts played harder during the regular season, they could've locked up HC and probably beaten the Lakers as HC played a big role in that series
3.)
The infamous Perk trade during 2010-11: Sorry folks, it might not be popular opinion, but this was BIG.
Before this deal, the Celts were the best team in the East. They had beaten Miami 3 times and it looked like no one was going to stop them.
After the trade, the team was never the same. I do recall the Celts winning some games right after they acquired Green/Krstic, but by the time they played Miami in the playoffs, they were badly missing Perk and his toughness.
Alot of people point to Shaq's injury as the reason why we came up short. This should've been expected when you acquire a 39 year old player who's a big man with a history of injury concerns.
4.)
Not landing David West and OJ Mayo: This one, I am not sure if you can blame Danny or anyone for that matter. I guess the only criticism you can put on Ainge is either he should've gotten someone else after West picked Indy and NOT listened to KG/PP about keeping the hobbled Ray Allen in the proposed OJ Mayo deal.
Would acquiring West or Mayo have helped the Celts beat Miami?: Tough one. I am thinking probably not. Lebron's game 6 performanc was so awesome, that I am not sure even Bill Russell in his prime would've been able to help the Celtics.
But make no mistake about it. Not being able to acquire another player didn't help during the 2011-12 season.
5.)
Once again, no trades during the 2012-13 season other than Jordan Crawford: Once again, other than acquiring Crawford (which didn't really do much) Danny was unable to acquire more talent to help the Celts. Both KMart and Birdman were out there, and they later ended up going to NY and Miami.
So, between the Celts playing 500 ball in the 2nd half of the 09-10 season and Ainge's trade deadline failures (both from the failed Perk deal or just failing to make a deal altogether to help the team) this is why we only saw one title during the new big 3 era.
Another title should've been won. I expect more from the greatest franchise in the NBA.