Wotherspoon was shown two yellow cards in the space of seven minutes in the second half after being adjudged to have fouled Danny Amankwaa and debutant Joaquim Adao in quick succession.
The St Johnstone manager has previously clashed with Dallas, condemning the official for a failure to award his side a penalty during a 1-0 defeat against Celtic last term.
However, Wright will refrain from taking it up with the Scottish Football Association’s head of refereeing John Fleming.
“Christophe Berra got away with fouls all day and doesn’t get talked to,” said Wright. “Then he sends David off when we thought it was a foul by the Hearts player [Adao]. But Berra plays for Scotland and David doesn’t.
“I don’t want to make it ‘the Andrew Dallas show’ because he made enough of that out there.
“I’m certainly not going to be phoning John Fleming about him because I’ve lost count of the times I’ve been on to him about Andrew Dallas. Luckily he’s not in charge for either of our next two games.
“Even after the ridiculous decision to send David off, we responded well and still should have got something out of the game.”
St Johnstone also had a strong claim for a penalty waved away in the first period when Berra appeared to block a Steven Anderson header with his arm.
“I don’t mind the penalty not being given if the decision was that it wasn’t intentional,” added Wright. “But Andrew Dallas clearly pointed to his shoulder when everyone could see it was a handball.”
Despite St Johnstone striking the bar through Chris Kane and forcing Hearts keeper Jon McLaughlin into a string of fine saves, Hearts claimed the smash-and-grab triumph thanks to David Milinkovic’s fifth goal of the season, 39 seconds after the interval.
“Jon has been good from almost day one,” said Hearts boss Craig Levein of man of the match McLaughlin, who is out of contract in the summer.
“I can only remember one game where he made a mistake. That was way back.
“I haven’t given up hope of keeping him. We have made an offer but he has had other offers from down south that are greater than we can afford to pay.
“He has not ruled it out and is considering his options. He will be hard to replace but there are other players out there - lots of them.”