He made a decision and assumed when making future NT versions this would be revised and updated with the times. I can only image that future teams looked at this and thought "someone chose 32GB for a reason, better not change it"...
Changes, especially in a large system with a large user base, require extensive testing, and even small changes may come with a lot of red tape. I don't know how things work at Microsoft, but I wouldn't be surprised if making changes to the UI for a technology that's being superseded anyway just didn't make anybody's list.