Hmm... I do tend to agree, PA in NV is just not worth it compared to something like Desert Ranger or Combat MKII. Benefits from wearing PA dont have to be so obvious, I mean it could be easy to have a PA that reduced water consumption, added night vision, built in living anatomy perk and so on (Medic Prototype is a great example of this). At present the DT and carry capacity increase isnt worth the slowdown, or the lack of stealth.
If you're wearing PA you generally don't care if they see you when you shoot them.
There are two main problems with PA in FO3 and F:NV: 1) their protective values are too close to those of Combat or Metal Armor and 2) a single-layer system
cannot properly emulate the level of protection Power Armor is supposed to provide.
PA in FO1&2 (all armors, in fact) used a three-layer system to determine how much protection it gave. One of these layers, Armor Class, is no longer applicable due to the shift from an accuracy-centric to a damage-centric combat system, and the other two (DT and DR) are being used individually but are really meant to be combined. PA is designed to first absorb the impact/heat of incoming rounds/beams, and then dissipate a certain amount of that damage that exceeds the absorption threshold; how much depends on the damage type and the suit's individual ratings against them. FO3 used a global DR rather than a variable one, but did not use DT, which meant that said DR was applied against every attack rather than only the stronger ones; this resulted in inanities like being able to die to a Raider wielding a Pool Cue while you were wearing full Hellfire Armor. F:NV, on the other hand, uses DT but not DR. While this blocks the Pool Cues, it fails to provide adequate protection against heavy attacks that DR would still work against, such as Ballistic Fists. As you can see, it is when the two work together that you really get to see how tough PA is meant to make the wearer; what gets past DT is reduced by DR, which allows PA to fulfill its design intent of negating the vast majority of incoming attacks.
The values for PA in the old system were far above even those of Combat Armor, which was the next best overall option, while in FO3 and F:NV, they're either equal or only a few points (10 or so at the outside) better. Given what PA is supposed to do their values should be more like double what CA can provide, however at the same time there aren't enough opponents with heavy weapons for that much additional DT to see a lot of use, and the ones that
are there have attacks that far exceed even
that much DT, so it would only be a partial solution at best.
I modded PA in my game to have significantly more DT and added DR as well, and it comes a lot closer to what PA is 'supposed' to be. I can still get killed while wearing it, which was also true in the first two games, but I'm covered against a much larger range of attacks than with a vanilla suit of the stuff. This makes the BoS Paladins a lot harder to kill as well, so attacking the Bunker isn't something to take lightly anymore, which I consider a good thing.