Surely Not,
You're absolutely correct in what you say - it would not be particularly cost effective to have steps operating in the same way as fixed airbridges and shadowing the rise and fall of the aircraft... however, in the company I worked for as Cabin Crew, it became policy that if there was a significant gap between the steps and the doorsill, to insist that (within reason) they were raised to meet the door once again. Most of the time this was fine, on the odd occasion it was going to prove impossible and would delay the aircraft by an unacceptable period of time by waiting to have the steps raised.
It was agreed that under these circumstances, so long as passengers could board safely once aware of the step, we would continue with boarding. However, we would normally have a crewmember outside on the steps to monitor and assist passengers as they boarded. To people who have not been Cabin Crew, you may imagine that passengers would notice a fairly obvious step and would deal with it in the correct manner! However, this is not always the case - as cabin crew all you can do is to minimise the danger so that should anything actually go wrong, you have done your very best to uphold all health and safety standards. At the least, if we were unable to get the steps moved, we would still complete a CSR which may hopefully limit the number of times it would happen at that airport in the future.
Once in a while things do go wrong which we can learn from - however, (and I don't know the facts in this tragedy so I'm not suggesting this is what happened) sometimes familiarity takes over and people get hurt or worse. This is why we have safety standards, they are there because somebody has been injured or killed before making the same mistake. Ignore them not only at your own peril, but at the peril of everybody in the large team that looks after a flight.
FJ2k