Wheldon died in a horrific 15-car crash at the Las Vegas Motor Speedway on Sunday, leaving fans stunned and plunging series officials into crisis management mode as the season-ending celebration turned to disaster.
England's Darren Turner, a former F1 test driver for McLaren, would replace Wheldon for this weekend's Gold Coast 600 race in Australia, organisers said on Tuesday.
"In Indy racing, there is simply nowhere to go. When an accident happens you are into the wall in a split second," Mansell told BBC Radio 5 live.
"To have 34 cars travelling at 220mph on a mile-and-a-half long circuit, there are too many cars on the track.
"The trouble is there are no small accidents when accidents happen. There were a number of rookie drivers and others driving in their first race of the season."
Mansell, who won the F1 world title in 1992 and the IndyCar title a year later, lauded Formula One for its safety measures. "This is why Formula 1 does an exemplary job," he said.
"The tarmac runs off so the driver has time to decelerate the car." Red Bull Formula One driver Mark Webber said IndyCar would learn from the accident and look to make improvements. "I think the pack racing element of it is particularly hazardous," Webber told reporters in Sydney.
"The single seaters, to be that tightly packed, to be rubbing each other at 350 kms an hour, that's what they are probably going to look into on a short oval.
"I've never raced on an oval, but I've spoken to a lot of my mates who have, and I know that it's something that they would like to improve.”
