In my opinion, the most useful order would be this:
Rally - Planes - Regular Troops - Alliance Gate Troops - Generals - Tactics [These to the left are the most commonly used deployments used in MP] - Mercs - Wonder Building Tactics - Stronghold TTs
Some people suggested having things disappear from your tray once you use them and shift everything left, but that I think would cause problems when you're trying to pick things out of the list and stuff keeps shifting. You're going to end up selecting the wrong one as stuff moves around. Better to keep it in place and grey it out like is done.
If you reverse the changes and go back to the way it was, while making minor QoL changes, that would be great because I don't remember seeing any post from anyone asking for 'improvements' to the troop tray as you suggested in your first post. You're not fooling anyone: putting TTs to the left is purely an attempt to get us to use them by accident.Just to set expectations: We can't quickly turn around a system that allows full customization for everyone or locking planes (I'd also be hesitant to lock planes due to considerations for SD devices that have full plane slots and the big red button). Major changes like those aren't being considered right now.
But, we have certainly heard your feedback and are looking at undoing most of the ordering changes. We're currently looking at a change to move Wonder Tactics to the end and to move Troop Tactics to not sit between planes/mainline. The result will more or less be a revert of the ordering changes while keeping some of the other QoL changes (like the removal of empty slots).