Somewhat confused as the motion systems haven't changed. I assume the motion pad wasn't correct to start with and more aggressive use caused the problem?
Over the years as old planes are retired and new fleets are added, simulators get swapped out. Some of the sim bays at my company go back decades, and even the "newer" ones were built before the new motion programs took effect. The original sims were never programmed to represent the full range of forces that would be felt by the crew during a full stall. The new programming, while much more representative, requires the sim to make much more aggressive motions to simulate those forces. Newton's law and all that, these now increased forces were never part of the specs when the floor mounting systems were designed. I suspect this was known in advance and those involved hope that the typically over-engineering that goes into aviation related products would handle the issue. Unfortunately not. I don't know if this is a problem everywhere, but eventually the concrete around some of our sims will need to be replaced.