Cramer expressed that regret one day after Thursday's release of more than 100 pages of internal Boeing communications, in which company employees boasted about bullying regulators to approve the now-grounded 737 Max without requiring pilots to undergo simulator training.
"I'm totally shocked," Cramer said on "Squawk on the Street." "I feel like a 'clown' and a 'monkey' defending everything. I was defending them more than they were defending themselves."
Cramer's use of the words "clown" and "monkey" evoked one of the newly public messages that one Boeing worker sent to another in April 2017 about the 737 Max, which read: "This airplane is designed by clowns who in turn are supervised by monkeys."
The entire Max fleet was grounded in March 2019 after the second of two deadly crashes within five months of each other involving those jets. The tragedies claimed 346 lives. The other crash happened in October 2018.
The messages Boeing released publicly Thursday had already been shared with the Federal Aviation Administration and lawmakers. The FAA said the messages did not reveal any new safety risks. Boeing said the messages "do not reflect the company we are and need to be, and they are completely unacceptable."
Cramer said Friday: "I think what was disturbing to a lot of us was we thought Boeing's culture had been one of the best. It turns out it wasn't." He added: "Now they have to make it the best. How quickly can you do it? Do you have to have someone from the outside?"
Boeing's new CEO, David Calhoun, a 10-year veteran of the company's board, is set to start Monday.
Last month, the company announced Calhoun as successor to Dennis Muilenburg, who had been chief executive officer since 2015 but was fired in December. Muilenburg was widely seen as botching the handling of the 737 Max crisis.
On Tuesday, in a reversal of its earlier stance, Boeing said it would recommend simulator training for pilots before the 737 Max can return to service.
Back in October, after Muilenburg had been stripped of his chairman role, Cramer said, "Wall Street got had," explaining that many analysts and he had thought that "once Boeing was free to tell its story, it was a good one." Cramer added, at the time, "That, I think, is no longer true."
Shares of Boeing, one of the 30 components of the Dow Jones Industrial Average, are down about 20% since the March crash that led to the worldwide Max grounding.
— CNBC's Leslie Josephs contributed to this report.