Your comment would be understandable if the team was comprised of the same players as it was 8 years ago. There isn't a single holdover from the 2000-01 season. This is not the same core group of players; it's not even close.
The Maloofs and Geoff Petrie either dealt every single player away to get better-fitting players back (Jason Williams, Scot Pollard, Corliss Williamson, Peja Stojakovic, Hedo Turkoglu, Doug Christie, Bobby Jackson, Nick Anderson?, Tony Delk?), or let free agents walk because they didn't fit the team plan (Vlade Divac, Jon Barry?, Darrick Martin, etc.). The lone exception would be Chris Webber, and he's not here anymore either, for whatever reason.
When it comes to keeping the same coach without winning a championship, do you realize that in the past 16 years, only 4 coaches have won championships? That leaves - in my estimation -probably 60 or so NBA head coaches that have NOT won championships.
Now, when you look at what Rick Adelman did with the Kings in his tenure here, there's two ways of grading his performance: 1) the most popular, as evidenced by your post, is Did he win a championship? By that criteria, he failed. Did not win a title, came close a couple of years in a row, but still didn't get it done. However, by that same criteria, almost every other coach in the NBA over the past decade and a half has failed as well. Jerry Sloan has been failing for almost 20 years now, but his tenure in Utah has NOT been a failure, not by any stretch of the imagination. And that's with his squad missing the playoffs completely the past two years.
The second way of grading, the more reasonable way: 2) Did he get the most out of his team? I would imagine that some would think he excelled at this, while some would say that he failed miserably. I'm in the middle, leaning towards the former. Some "talented" players that never materialized as quality pieces in Sacramento: Hedo Turkoglu, Gerald Wallace, etc. Some players that turned into more than they ever were elsewhere in Sacramento: Doug Christie, Keon Clark, Vlade Divac, Damon Jones, Bobby Jackson, Scot Pollard, etc.
If you're sole criteria for grading your head coach is whether he won a championship or not, you're not going to hold on to many head coaches, because the overwhelming majority of coaches in today's NBA have NOT won championships. Bottom line, Rick Adelman didn't fail because he didn't win a title. I would argue that he did as much as he could with what he was given (for 8 consecutive years, he took an offensive-oriented team to the playoffs, and contended for a championship in at least three of those years). If the Maloofs or anyone else expects to squeeze blood out of a turnip and turn an offensive-minded team into a defensive-minded championship contender, they are in for a hell of a season, emphasis being on HELL.