Target Acquisition Delay is even worst for the game than Ghost Heat. It doesn't affect the core problems of the Information Warfare Pillar, it is applied inconsistently over battlemechs in the PTS, it's effects are basically ignor-able by the majority of the player base, it makes things significantly worse for new players, it's another massive debuff of already weak weapons, and it makes I.W.P matter less than ever before. An explanation for each complaint:
The core problem with the Information Warfare Pillar is that the information it provides doesn't really matter much. Most of the information about a mech's build can be obtained through observation on the battlefield and time to kill is low enough that it's not worth the effort to try and hit a mech's weak points. T.A.D. doesn't do anything to address these issues.
I've looked through the data quirks from the PTS, and placement of TAD quirks are all over the place. There doesn't seem to be a common theme and direction to their placement. Maybe I'm just missing something, but why do scout mechs like the Commando and LRM-Boats like the Catapult have TAD quirks?
TAD quirks only delay the addition of a mech's location to your HUD, mini-map and it's availability for target locks. With the prevalence of ECM, the majority of experienced players are used to locating and hitting mechs without the aid of their HUD. The TAD quirks will have zero effect on their play.
New players don't have those skill though, and they don't know the maps or were opponents are liking to show up. TAD quirks will make it significantly harder for new players to learn these things because it is withholding the information they need to learn those skills, likely for long enough effort that they will be killed.
The weapons that TAD will effect most are LRMs and SSRMs, which are already some of the weakest in the game. The only ones that are relevant are massed Clan-SSRM builds, and there are other, better ways to deal with them, such as "ghost heat" or stagger firing SSRMs.
This is a big one for me. At a fundamental level TAD makes IWP worst because it gives players less time to use the Information Warfare Pillar. Even ignoring the issues with time to kill which would result in mechs being destroyed before they had gotten past their TAD time, the way to fix a broken motorcyle is not to start taking off one of the tires. Whatever other IWP systems get built, TAD will always reduce their usefulness, as we will always be unable to use them for those key few seconds when a battle starts. It will teach players to ignore IWP because it won't be there when they need it. It is literally taking away a tool that players want to be able to use to achieve their goals. It is the worse possible option to implement if your goal is to make IWP more interesting and important in game play other than completely removing the system entirely.
TL;DR: Yes, Target Acquisition Delay really is that bad.