Coaching in the big leagues is all about conformity. It's about as conservative a brotherhood as you'll find. You don't get to that point of being a professional coach without having attended thousands of hours of clinics where they all preach from the same bible. Any creativity that you may have is knocked out of you.
The difference in schemes between any two NBA coaches are minimal at best.
I've been a coach of 4 different sports for 15 years, and have managed to take previous year tier 3 teams and have them beating or competing with tier 1 teams the next season. How? A little creativity and breaking the unconventional? One year in little league baseball I noticed how infrequent these 12 year olds were hitting it to the outfield, so I went with a permanent extra infielder and only 2 outfielders. My outfielders were super speedy little kids but couldn't catch fly balls consistently so I only had two of them out there and all they really did was chase balls down whenever someone did hit it to the outfield. But my extra infielder was able to make many more plays and also stop balls from rolling out into the field and extra base hits. It worked out really well, but you can't imagine the heat I got from other coaches, opposing parents, and even parents on my team. It was unconventional and against the spirit of the game (show me in the rules where it says exactly where all your players need to stand).
I'll admit I was young and eventually relented to the pressures and went back to a conventional system and only pulled in the extra infielder on certain situations.
Look at the heat Bill Belichick took for going for it on 4th down vs Indy inside his 30 earlier this season. Even though there's a ton of theory on puntless football being a winning strategy (see: highschool wins state without punting http://highschool.rivals.com/content.asp?CID=892888 or a bunch of probability debates http://www.footballoutsiders.com/stat-analysis/2006/never-punting) Belichick has been lambasted. And that's just on one play! Imagine if Belichick did that on every drive?
Here's another great story of how David beat Goliath by Malcolm Gladwell that I posted a few days ago, about a basketball coach who didn't grow up watching hoops and implemented his own strategy of a true full court press every single play. Eventually he had Roger Craig (former star running back of the 49ers) and his daughter help him coach their team in the state championships. However opposing teams and refs got so furious with his strategy, he returned back to a conventional strategy in the finals and got killed. It's a really great read: http://www.gladwell.com/2009/2009_05_11_a_david.html
So at the end of the day, coaches behaviours are driven by expecations and conformity. If fans had the guts too they'd be cheering Belichick's decision. The difference between any two NBA coaches is like choosing between a Macintosh or a Granny Smith.
Unfortunately it takes guts to go unconventional. It's always better to be the second person to do something than be a pioneer.