Same thing happened here 2 years ago. My company (600 employees - median salary about 175K) had a GREAT 401k putting aside 20% more than base pay into our 401k without any contribution on our part. A couple years ago we were bought by a large engineering firm (20,000 employees - median salary about $60K). They only do a 3% match, which is a huge disparity compared to ours.
Apparently we didn't pass this IRS test, because our 600 employees bring the average way up on retirement benefits. So they had to adjust things to fit the law. To do so they reduced the automatic contribution to 9.5% and created a 6 to 5 matching. Essentially, you can still get the 20% but now you have to contribute 6% to get 14.5% from the company. Amounted to a 5.5% paycut through benefits.
I guess this is the IRS trying to reduce the ability of Executive level employees from taking advantage of 401k harbors for tax advantages. Sucks when the implementation of something like this affects a company like mine across the board (not just management), when all that has changed is who owns us.
Reminds me a bit of Title 9. Great rule in theory, but in practice it was implemented opposite of how it was intended. It required that schools have an equal male to female sports scholarship ratio. Instead of creating more female sports scholarships [intention], schools just cut their men's programs [implementation] to adhere to the new rule.