And he is hoping that in 12 months time Villa will have a big enough squad to sustain a push for domestic and European glory.
O'Neill, who has left eight first-team players at home for Thursday's last-32 second-leg clash with CSKA Moscow, said: "I have no regrets whatsoever about entering the UEFA Cup.
"I am delighted because these experiences will definitely stand us in good stead.
"I am not just talking about the younger players like Gabby (Agbonlahor) and Ashley (Young) but also ones who have played a lot of international football like Gareth Barry and Stiliyan Petrov.
"I think the European games at club level have been terrific for everyone so there are no regrets. In many aspects, it has helped us immensely.
"Maybe this time next year, all these experiences that we have had will stand us in good stead."
O'Neill added: "If we are still involved in Europe by this time next year, hopefully we will have the size of squad to be involved in these things.
"But the chairman (Randy Lerner) has entrusted me in the running of the football club. This is the way I am doing it at the minute.
"The Premier League, given the position we are in, is very important. Taking everything into account, we have to prioritise."
Prem To Finish In Top 4 2008/09 Win Outright: Aston Villa 8/13