This is true, but the '98 Seville's had the adaptive seating, the newly introduced CVRSS suspension system, massaging seats, the electronic gauges, performance algorithm shifting, the late '02-'03 STS with Magneride, and the pretty advanced G-body structure underneath. I think Cadillac showcased the '98 as more of a technical luxury sedan whereas the '92 was more of something that showcased a new style of Cadillac's to come.
Both improved Cadillac's bottom line, and most auto rags were impressed with both cars when they were introduced. I still prefer my '00 STS to the newest of Cadillac's cars, with the only exception being the XLR-V.