Big yes to healthy Davis but he spend most of his regular season time injured which means Lakers is playing without him on many games so it’s much better to have decent replacement that is constantly playing more games a year than a glass cannon player.
Lakers probably thinking that they should do this trade while Davis is still valuable that even Mavs trade their superstar Luka that carrying them for so many years.
Yes, injuries are a major problem for Davis. A couple seasons ago, nobody was surprised that Davis might miss half of the regular season just because of injuries. However, it's worth noting that he's had some improvement in that regard. For example, last season, Davis played in 76 of 82 regular season games. That's really a lot of games for him, or rather it's his career best. Besides, he hasn't missed many games during the current season.