I am against lessening the impact of the regular season. Less teams in the playoffs means regular season games that are much more must win situations.
I have been reading about topological approaches to questions like this one ie how many truly competitive situations regarding the playoffs there could be. In the vein I will try and demonstrate how you are wrong.
Competition comes in three forms. Challenge to division leads, people struggling for the last spot, and jockeying for position for home field advantage. Those are the vertex, edges and sides.
You will still see 4 division races so those matchups are still possible. You will still have a finite number of wild card slots and so there will still be jockeying for those last spots just as there were before. Now otoh there are 7 teams jockeying for position versus 6. That in theory presents one more team competing for HFA. In fact the symmetry looks exactly the same at least from the end points of top teams and bottom teams. It is just longer, so to speak, because of the additional team or teams per conference. Longer speaks to more quantity or more places where competition is possible.
I would argue that expansion means more competition unless you dont think coaches find HFA important enough to compete over.