When I got my 80 gallon Glass tank, the plastic center brace had already been removed.
It's worked fine for me--just a slight bulge in center (but not noticeable unless I pull out a tape measure). The tank has been moved twice in 3 years now, and no issues. +The brace was probably removed 2-3 years before I bought it too.
Note: when I bought the tank it was sitting (fully stocked) on a stand designed for a 55 gallon tank! (i.e. it was 6" too short along the whole back-side) So it's been through some extra "stress-testing" already!