Reus has been a loyal servant to the Dortmund cause since joining from Borussia Monchengladbach in the summer of 2012.
The 31-year-old Germany international has made 274 appearances and scored 131 goals in his time at the Signal Iduna Park but has been dogged by injury problems in recent seasons.
Dortmund looked beyond Reus’ fitness issues to hand him the captaincy in 2018 but Hamann believes Lucien Favre’s men need a consistent leader to help them mount a title challenge to Bayern Munich, who have won the Bundesliga for the last eight seasons.
Reus made just 19 Bundesliga appearances last season, scoring 11 goals and has featured five times already in the current campaign.
"Mentality, leadership. You can't have a captain who only makes half of the games,” the former Liverpool and Germany midfielder told Sky Sports.
"I didn't understand why they didn't take the captain's armband off him in the summer. The other question is whether I would have given it to him two years ago. You have a player that you have to pull along."
He added: "Dortmund is better at the moment without Reus. That has to do with the fact that [Giovanni] Reyna is in good shape, that [Erling] Haaland is in very good shape, [Julian] Brandt played well and with [Jadon] Sancho they have an outstanding player."
"With Hummels, you have a brilliant leader who has shown in the past that he can lead teams, that he has leadership qualities, that he can speak up, that he can inspire people."
