Dortmund has a good team and they are not weak at all. Even after selling many young and talented players in the last years, still, Dortmund was always racing in the top side of the La Liga with Bayern Munich while they don't spend too much money like Bayern Munich.
Also, Dortmund is getting what they need, they are racing in one of the best leagues with one of the best teams while they are also making a good amount of money which is what they want,
For sure they want and wanted to make some money in the last years but they also wanted to get the german title.
And at some stage its anymore possible to hold very good young players when they will get some huge more money at other clubs.
If Dortmund would be tried to hold all this players they would be run out of money and maybe dosnt stay as good as they are right now financially.
Personally, I'm proud of Dortmund, they understand their game and the tactics to win and also get to make the money, I will never crucify them for it. And as for the record, they are a very strong club to reckon with, they are always finishing atop regardless of how they use young players, and they actually understand the game and the business. Even at their current status, they are just 2 points below the top spot, which is the same level as Bayern Munich as well.
I believe that if Dortmund could be more serious this season, they might toughly displace Bayern Munich and win the season. I judge this by how Bayern plays, it might not be obvious yet but it's not perfectly like when they are in their utmost form.