Our goal is that all Tactics feel like they’re worth bringing
I do not see how such changes in the Tactics would achieve that. Instead, it may only make Betrayal, Sabotage and Protect less worth bringing without making the rest of the Tactics more worth bringing, resulting in further lessening to the diversification of Tactics that a player would use, which contradicts with the stated goal of the changes. I personally think that reducing the training time for those less popular Tactics would encourage players to use them more frequently. For example, if the training time for First Aid is reduced by half or three quarters, I would consider using it instead of the Protect Tactic or Healer troops.
As for addressing the issue of offence-defense imbalance, the changes to the Tactics would overdo it. The main reason for the offence-defense imbalance that I have observed playing this game for 1.5 years is that most players(including myself) focus on offense much more than defense. This is mainly due to the amount of resources generated through not offensive means is miserably low in relative to attacking others, which makes it a very great incentive to focus on offense, as having more advanced offensive stuffs enable players to attack stronger bases. Moreover, the amount of time and workers needed to upgrade defensive infrastructures(as a whole, I'm not referring to a single building) is much more than that of the offensive stuffs, making it even less attractive to spend time in upgrading defensive stuffs. Honestly speaking, it's not that easy for a maxed offense player to clear a maxed defense base of the same Age if the defending base is designed properly.
With the introduction of the University, the Sniper Tower(esp when there are multiple Sniper Towers in the later Ages), the Stronghold(which allows the use of Troop Tactics on defense in WW) and the purchasable limited time Bazooka Tower(which is no doubt overpowered), the gap between offense and defense has already been significantly narrowed if not turned around.
Looking at other publicly accessible official and unofficial player-initiated DomiNations communities that I visit on a daily basis, I see very much the same scenario as here: a significantly much louder voice against the changes to Tactics than that of those that support.
@Nexon/BHG, I am really curious to know which and what community gave you the feedback that changes should be made to the Tactics? With such changes and the long overdue but still unsolved issue of mismatching and sandbagging in WW(the core feature of DomiNations), the game is becoming more and more unenjoyable if not unplayable for the majority of the players.