O'Connell has been ruled out of the second and third Tests in Melbourne and Sydney after fracturing his arm in the 23-21 victory over the Wallabies at Suncorp Stadium.
"Paul's an intimidating figure when you see him standing across from you in a lineout. He attracts a lot of attention. He'll be a big loss to their camp and it's a shame," said Hooper.
"He finished the game with a broken arm so you can see how much he wants to be there.
"There will be someone who steps in who is just as good. Maybe they won't bring the same emotional or spiritual thing that he'd bring, but skill-wise it will be the same."
While O'Connell will miss the business end of the series, Australia were celebrating the availability of captain James Horwill.
Horwill was controversially cleared of stamping on Alun-Wyn Jones at the Suncorp Stadium by a disciplinary hearing on Sunday evening.
"It was great to keep our skipper. He's a massive motivational part of our team," added Hooper.
"We get a lot of drive from him in the words he says and his presence on the field.
"We know that O'Connell was a big player for the Lions, very similar to Horwill."