My impression, if I might say, on the subject of omnibus bills...I hadn't meant to bring this up, but looking at it.... I have an interest in the issue of administrative law. I'm an editor of the Administrative Law Review out of Washington, D.C. It's clear that administrative law and the need for administrative tribunals arise with the complexity of the regulatory state, which has exploded over the course of the 20th century. As far as I can see, it is unlikely to slow down in the 21st century. I think it is simply in the nature of an increasingly complex society with more interactions.
That being said, I think omnibus bills are a reflection of the practical fact that it's hard to get the larger number of bills we need through our legislative process in the requisite time. This is compared to the situation a century ago, let alone a century and a half, when the Fathers of Confederation were designing it.