Trapattoni's five-year tenure ended on Wednesday morning, with a mutual decision reached after a 1-0 defeat in Austria the previous evening all but ended Ireland's hopes of qualifying for the 2014 World Cup finals.
The 74-year-old gave Keogh his first senior cap against Poland in a friendly at the Aviva Stadium in February - Keogh's Derby team-mates Conor Sammon and Jeff Hendrick also made their debuts that night in a 2-0 win for the Republic.
The Rams skipper, overlooked for this month's qualifiers, says he owes Trapattoni a debt of gratitude and praised the veteran's work while in the job - but he believes the decision to replace him is ultimately the right one.
"I have a lot to thank him for because he gave me my debut for Ireland and for that I owe him a lot, really. I thank him for that," said Keogh.
"With the campaign, the last two games - losing at home to Sweden and then in Austria - have not been great and maybe it is time for a change.
"But I think if you look at his record he has had a good spell and he has been great for the country and he leaves with his head held high."
Those losses to Sweden and Austria have left Ireland with only a purely mathematical possibility of overhauling the Swedes to snatch second place behind Germany in Group C.
Successive losses in the space of five days cost Trapattoni his job but Keogh believes the damage was done back in March, when the Republic conceded an injury-time equaliser at home to Austria to draw 2-2.
"That deflated the whole campaign, really," said the 27-year-old. "Victory there would have seen us put our stamp on that second spot, which I think was a realistic aim for this campaign when you look at the other teams in the group. Obviously Germany are a world-class team and were always favourites.
"The last two games have been a kick in the teeth, but Austria at home was pivotal, and unfortunately for the manager it has cost him."
Keogh added: "With a new manager coming in now it is a clean slate for everyone.
"I have heard a few names like Martin O'Neill and Mick McCarthy and if someone like that got the job it would be great because they are both good managers."