Dirk Nowitzki will obviously go down as the Dallas Mavericks best player in their franchise history. He lead them to a title in 2011, and was a 14-time All-Star. Like Kobe Bryant, he spent his entire career in Dallas and was a fan-favorite and continues to be to this day.
It also appears he was quite loyal. It was reported that in 2014 he rejected an offer from the Lakers that was for three years and a cool $92 million. He ended up taking a more team-friendly deal with Dallas and retired there after the 2018-2019 season.
For the Lakers, the prospect of Nowitzki and Bryant playing out their twilight years together would have been and enjoyable for Laker fans. Perhaps though, developing the young talent they would then use to acquire bigger pieces down the road, worked out better. It may have been more enjoyable for Bryant and company, but Nowitzki's value over replacement player numbers dipped considerably in these aforementioned years. It probably worked out best for Laker fans, and best for the Dallas Mavericks to have their franchise's most beloved player retire a Maverick.