UEFA recently altered the entry criteria to the Europa League by guaranteeing the domestic cup winners of the top seven nations, according to its coefficients, a place in the group stage of the competition rather than only a play-off berth.
From next season, the Europa League winner will qualify for the subsequent season's Champions League, but Hubner believes a similar incentive should apply to the DFB-Pokal, won by Bayern Munich and Borussia Dortmund in the past two seasons.
"It could be an idea for the cup winner of all European leagues to play in the Champions League and not the Europa League," he told Germany's Sport Bild magazine.
"That way, other clubs would also have the chance to earn big revenue."
Stuttgart were beaten finalists in Germany's cup competition last season and they subsequently failed to reach the group stage of the Europa League with Freiburg, who finished fifth in the Bundesliga, taking the cup winners' automatic berth in the group stage of Europe's secondary club competition.
Frankfurt, who finished sixth in the Bundesliga last season, are already through to the knockout stages of the Europa League, but cannot expect the same kind of riches they could earn from merely appearing in the group stage of the Champions League, even if they go all the way to the Turin final.