Surely there are ways to get rid of it without the transition being so traumatic. For example, the change could be announced a few years prior, and the downtime could go down by an hour per year.
To put things into perspective, the company I worked for responded to bug reports by hiring a team of people whose role was to manually alter the database any time a customer reported a data problem. Dozens of times per day. In other words, instead of fixing the software, it somehow became a reasonable idea to dedicate employees to fixing the symptoms by hand. It made sense in hindsight: they were making so much money that they took the path of least resistance. Paying employees to fix the problem immediately was quicker than trying to hunt down a competent programmer to try to fix the problem without causing more problems.
The change would be traumatic no matter how long they are given to plan for it.
Oh, here's another reason I forgot to mention: You can capture huge profits by exploiting the opening and closing few seconds of the market. A huge portion of all daily trades happen within the first few and last few seconds of the day. So there's a financial incentive to leave things as they are.
