GM left the cabin filters out after 2003. My thought is, people were not replacing them and a clogged filter causes more complaints than no filter?
After 2004 the fuel filter was moved to the fuel tank. The filter is now a part of the fuel pump and is not separately replaceable. Supposedly the filter is large enough to accommodate many miles without replacement. I have seen several of these trucks with far more than 150,000 miles, the original filter in place and no problem.
I believe like most auto manufacturers, GM is trying to lower maintenance cost. I too like being able to replace these filters on my own vehicles. Perhaps its just the way things are going?