Releasing products on a set date is a tradition. Catalog's are an advertising product. This tradition most likely stems from good businesses practice. IMHO its creates anticipation which is good for advertising, it's orderly which probably makes it cost effective and it's fair (consumers have equal opportunity to get a catalog and dealers don't get a run on catalogs).
Not that this is a great analogy but why do you have a lineup and a starting gun at the start of a race. You could simply have each horse run individually and the fastest wins. Fairness comes to mind and it's probably hard to sell tickets to that kind of race, seems like an anticipation killer and not a money maker. But there is no debate on how to start a race because of tradition. It's the way it's done.
If catalog's are being released early, it's a breaking of tradition. Most traditions are in place for good reasons for all.