Frankly, I think the new version of the fluff makes a lot more sense. For the Templars to universally hate psykers was inconsistent with the fact that they needed astropaths and navigators. The famous Templar absolutism seemed to be making an odd exception there. Also, it stated they made an exception for the Grey Knights even though the latest GK Codex made it very clear that they went to extremes to keep their existence secret, even to the point of mind-wiping Astartes who knew of them. (And please, no Matt Ward hate replies to that. Like it or not, it's canon now and it needed to be dealt with.)
With 6th edition making it possible to mix Codexes (codices?) in a single list, the Templars were at a severe disadvantage by uniquely having no option for taking Librarians with no alternative benefit to balance it. This eliminates that problem and I'm fine with it.
Tactical inflexibility is not an advantage, yet we sort of told ourselves that Templar strength came from that sort of attitude.
Let's be honest and talk about the elephant in the living room. For several years I've been a BT player and participated in BT forums, talked BT tactics and generally was one of those BT fans who embraced the fluff because it was ours, and approached a crappy codex with as positive an attitude as we could muster. Yes, it was crappy, It was horrible. It was a sloppy cut & paste job from the 4th Edition Codex Space Marines but with fewer options. We had exactly one troop choice, no Librarians and as the editions evolved the only things we had going for us were the vows and a few unique loadout options. It wasn't enough.
Creative and daring BT players could make a serviceable list and we all took on the "can do" attitude of getting wins with a substandard codex as a mark of skill and honor, but on some level we all felt neglected and resented it. (Rightly so.) But the unpleasant reality is that while BT fans were zealous and dedicated, we were not in sufficiently large numbers to merit more attention from GW marketing. Sorry, but that's how it is.
I didn't want to have the BTs get rolled into C:SM but I'm satisfied with the result. I think the absolute hatred of all psykers painted us into a corner rules-wise that has now been fixed satisfactorily. Is it a retcon? Yes. A big one if you're a Templar, insignificant if you're anyone else. Has GW retconned before? Hell yeah. Leman Russ used to be an Imperial Guardsman. The Sisters of Battle used to be all about hunting down and destroying renegade Space Marine chapters. There used to be Squats. Space Marines used to have access to vortex grenades. There used to be Spartan tanks as dedicated transports for Terminators. The game changes. The fluff changes. It evolves. I think it's been getting better.
Yes, I'll be fielding a Blood Ravens Librarian as part of a detachment to my Black Templars. I'll be winning games, and I'll be ignoring haters who tell me I'm somehow "un-Templar" for making that choice. I don't play this game to satisfy them.
As for the worship of the Emperor as a god... It used to be that ALL Space Marines considered the Emperor a god. The fluff has been moving away from that, especially with the Horus Heresy novels. The Templars' attitude toward the Emperor was CLEARLY one of worship in the 4th Edition Codex with "holy" this and "blessed " that and so on. That didn't make them all that unique though. Just look at some older novels in which Space Marines outright pray to the Emperor. The boltgun was described in an older Space Marine source as the "holy bolter" and vehicles weren't just vehicles, they were regarded as living things with a spirit, not just by the Mechanicum but by the Marines as well.
All of that fluff has been changing, and that's just how it is.
That said, if you want to play your Templars a certain way, where they avoid witches or don't pray to the Emperor or whatever, then more power to you. Your army, play it how you like. Your fluff is your fluff. I have -zero- criticism against you. I do however, take exception to people who want to criticize others' choices, as if their own fluff interpretation were the only one. The galaxy of the 41st Millennium is big enough for all of us.