The former Inter Milan defender made his move last week to Germany.
"Young foreign players go far in Serie A," Donati told Tuttosport.
"For example, Dutch player Kevin Strootman is really sought-after in Italy, but the semi-final showed we are better than the Dutch, as we beat them.
"The clubs must have faith in young Italian players. If you give the young foreign imports a chance, then why not a young Italian who has a silver medal in the European Under-21 Championship?
"I would've appreciated returning to Inter and playing in Serie A, but there were no concrete options for me in Italy.
"When Bayer Leverkusen offered me a four-year contract, I couldn't turn it down. There is disappointment at not playing in Serie A, but I am much happier to have the opportunity of playing in the Champions League."