There were several missing pieces that have not allowed the Nets to get over the championship hump in the Kidd era. Sure they made the finals two straight years, but the East was ridiculously weak in this time, and it showed by the way we got stomped in consecutive years by LA and SA.
VCWannabe, you say that a lack of offense way crucial in the Nets not winning a championship, but I have to disagree. Their defense was the Nets' main strength, but they were also a very solid offensive team, scoring on the fast-break at ease. The Nets were by far the best fast-break team until Nash came to the Suns and Kidd got injured. Also, with guys like KVH, Lucius Harris and Rogers, we had a very offensively gifted bench.
No, the bane of the Nets' title runs in the Kidd era was not offense (as Detroit proved that defense is just as, if not more important in title runs), our problems can be attributed to any one, or even all of four key factors:
1) We lacked a dominating big-man. K-Mart was great, but his offensive game in the post was border-line awful (especially in the finals). We had Mutombo who was old and awful on O, and Collins who did a good job on Shaq but not much else. KVH, and Rogers could pretty much only shoot. Look at the last 4 teams to win a 'chip: We have LA with Shaq, SA with TD, Detroit with the combo of the Wallaces, and Miami with an old Shaq, but still Shaq none-the-less. We never really had a go-to big guy in the post to make the D collapse down (thankfully we know have Krstic).
2) We lacked a go-to guy on the perimeter until Carter came along. In the two finals' we had nobody who could get a bucket when needed, create their own shot or take the ball when the game is on the line. Kidd was great, but he just didn't have a sufficeable shot, Kittles can't create, and RJ was still too young and inexperienced. If a team doesn't have a dominating post player, the at least need a superstar wing player (a la Jordan's Bulls), and we just didn't have that during our runs.
4) Young, inexperienced coaches. I look at the last four teams that won a 'chip, and I look whos coaching them. Jackson, Poppovich, Brown and Riley. No disrespect to Scott and Frank, but they just don't have that experience. Look what happened to the Heat when Riley took over for SVG. Experience is crucial. Also, it doesn't help when your star player and coach can't seem to get along (Scott and Kidd).
4) Our fans. When you can't even sell out your arena in the NBA finals, you know you have brutal fans. I mean, the players had to notice the empty seats in a championship game, and it might have somewhat affected their morale. I don't expect Arco here, but that was just plain terrible.
Anyways, IMO, those were the missing pieces which kept the Nets from winning a championship in the Kidd era.