Debris clouds are used in the new scenarios that came with the 2400 and decimator, and not as a replacement for the existing asteroids. You're free to use them in casual play for however you like though.

Wrong. Page 2 of the rules in the Decimator read as follows:

"Debris clouds are obstacles as described in the core rulebook with the following exceptions...."

Therefore, since they fall in the same category as asteroids, they are legal for tournaments as well. They have not updated the tournament rules to indicate as much, but since they are labeled as such, they should be legal as they are considered the same type of components found in the core rules.

In the Setup Procedure and Squad Deployment sections of the tournament rules there is no mention of "obstacles". These sections specifically call out "asteroids" instead. They also mention needing to use one of each asteroid that comes with the core set.

Assuming that these are interchangeable components is a huge stretch.

A September FAQ included answers to other Wave 5 questions and rule clarifications and they weren't released yet, so it's not as much an "out of date issue" as they may not have decided at that time.

Not having debris clouds mentioned in the tournament rules isn't a sign that FFG was undecided on what to do with them. There was no change required in the tournament rules because there is nothing that was ambiguous about the use of asteroids during setup. Since there is nothing that would need to change to keep debris fields out of tournament play there were no changes made.

Also in terms of wanting initiative I would argue that there is already a skew towards taking initiative, with only niche low PS Bomber squads sometimes not wanting initiative, and even then its only sometimes. My suggestion would only further add to the existing bias towards taking initiative.

Unless I've got something with a turret I almost never want initiative against a Phantom if I've got something that ties it for PS. I pretty much never want it if I'm flying arc dodging ships either. When I'm flying a Phantom I only ever want initiative against turrets. I'd say I probably want the other guy to have initiative about as frequently as I want it.