The midfielder was sold to Fulham earlier this summer.
"A lot," Arteta replied when asked if selling Smith Rowe was disappointing. "When I had the talk with Emile, I really felt it.
"First of all because I have huge gratitude because he came into the team at a tough moment. I think he was the player that made our supporters and the team click, in a way. I don't know how to explain it but that was my feeling. Something changed when he came in the team. He created a different energy straight away.
"And I have a feeling like 'argh', that I have not got the best out of him. Obviously a lot of things happened in that time.
"From my side it was really sad, because I know how those boys feel when they are in that building, how hard everyone works to get them close to the first team, so I feel a huge responsibility to give them the chance. And now, can they sustain this level and make us better? That is the idea."