Ianchi was sent off for dissent when he argued with officials after Andrea Belotti's 88th-minute goal was disallowed for a foul on Yuto Nagatomo.
With the game poised at 1-1 after Mateo Kovacic cancelled out Franco Vazquez's early opener, Belott's goal would likely have been decisive.
And few could have argued that the home side were worthy of all three points. Vazquez could have added two more goals in the second half but it was those wasted chances that left his manager wondering what might have been as he watched the closing minutes from the tunnel.
"I was wrong to protest, but from the touchline it didn't look like much of a push," Ianchi told Sky Sport Italia regarding his reaction to the disallowed goal.
"The important thing is my team was always in the game against a great side like Inter, always tried to score goals.
"It's just a shame as towards the end we believed in our chances of victory, but didn't finalise those three or four clear opportunities.
"We pressed them high up the field, but unfortunately in the first half misplaced several passes that would've led to counter-attacks. It was the approach we wanted, seeking three points from start to finish.
"We need to be more clinical in future, as we can't keep wasting this many chances."
The draw means Palermo's search for a first win since their return to Serie A goes on.
Despite those missed chances, he has been encouraged by the progress of Vazquez, who robbed Nemanja Vidic to score an opening goal of his own making before hitting the crossbar in the second half.
"He already impressed last season, can give us alternatives and plays between the lines. We just all have to be more decisive," added Iachini.
"In my view [Paulo] Dybala is a [Vincenzo] Montella or Pepito Rossi style striker who can still achieve a great deal once he learns to pick the right pass or the right finish.
"Belotti is only 20 years old, so we are helping him to grow and once the whole team has more balance he'll get more playing time. Right now he is very useful with fresh legs when we need a push for the result late on, to change things up."