Actually, the regular season record is VERY important, in that it determines home court advantage.
As we witnessed with the 2008 Championship team, had we not solidified home court advantage, the outcome of the 2008 playoffs may have been very different, (in fact, most assuredly would have been). I do agree that winning the championship is not predicated on home court advantage, nor is it assured in any way, but in this highly competitive NBA that exists today, every little bit helps, and home court advantage can easily be enough to turn the tide.
Not only that, but a superior record can be a big psychological boost to the team that earns it, and the opposite for their opponents. Nothing is etched in stone, and all this is speculation, but I can honestly say that I prefer we have the best record possible, and hopefully the best record in the NBA. Does it guarantee a championship? Not at all, but I much rather go with the shorter odds ... and I love to have our boys in their own "house" as much as possible!