As someone who only recently finished his first SoK run and therefore am still on the level of red/gold RofL gear i want to give my opion aswell. I can understand the desire to make the older content more viable and make it easier for people to catch up to the lategame content. Since it doesn't affect me, i won't talk about titles.
Concerning the Buff duration nerf, ill be honest (even if many will hate me for this), i like the idea alot since in my opinion, its a shame that entire raids are easily cleared by just bursting everything down without any need to play mechanics. This will atleast make this a little harder to burst down bosses when damage is tight, but i know the playerbase for long enough that this will mostlikely only lead to further discrimination of weaker players, because people will exclude them from raids in favor of stronger players that are able to burst the bosses in the lowered timeframe.
The AC nerf, might have been with good intention, but i feel it won't lead to the wanted outcome and here's why:
Since i fairly in depts looked at the early game on the server i want to make a distinction for players that want to progress and buildup their char through the content and those that buy up from the auction house. (Those, not interested in lenghty explanations, skip this next section)
The optimal buildup strategy i found would be buying the PS gear and stat them with PS stats and easily obtained arcadia stats. The game gives you a sadly less known way of entereing the mid game in tikal easy, providing you with tikal stats and the first cores. DF awakened proves to be easy aswell even for small groups for the 2nd core and ToS provides you with possible Inferno stats. From here on out, it becomes difficult. Gorge is still extremely challenging and run only rarely while rofl is a huge stepup from inferno (normal mode might be an option but not well known, nor does it drop the much needed core). To progress to DC and further raids, RofL has to be farmed ALOT, but getting on a level, where you can farm RofL consistently seems to require RofL gear already or players that do all the work for you. But in any case it will take atleast 80 runs of each of the 5 Raids for full gold gear. a few more for weapons.
By utilizing the auction house, people might reduce this number or skip it entirely, but by reduction of AC in almost all Raids that are farmed, you even cut the income of players in this progression level, making the way up to the endgame even harder. I understand that the current numbers of AC rewards in raids lead to a to high income in this currency, which is why i won't even suggest reverting this change but i want to make some suggestions that will actually benefit progressing players, while mostly leaving the endgame unaffected in my opinion.
1. To compensate the lowered income for Rofl or below players, i suggest lowering the costs of the AC to memento trade aswell. 2500 or 3000 AC for 5000 mementos would greatly benefit players that can't easily make alot of AC and therefor give them a more accessible diamond income. The daily limit of 1 trade on the other hand will prevent highend players to reap higher benefits.
2. Adjust cores needed, by lowering the value of cores necessary for gold gear. In my opinion 5 cores for a 100% gold upgrade chance would be plenty and prevent people from having to stay on this level for such an enormous long time. But even lowering it to 8, would help people alot already. Add a core drop to RofL normal mode to make it easier for people to progress to RofL hard. Honestly i don't even understand why it's not there. Alternatively to the lower amount of cores needed, you might want to think about droping 1/2/3 cores for RofL normal/hard/awakened respectively.
3. In alignment of the suggested RofL changes, i want to recommend the addition of inferno easy and Gorge easy, aswell as increasing the AC for gorge again. Gorge is highly unpopular as it is now. It's to long and hard for way to low rewards. Both easy variants should drop cores. If you decide against lowering the amount of cores necessary, you should consider doubling up the core drops for the current raids. I would recommend splitting the 2 cores to reward the first after boss 3 in Inferno and after boss 4 in gorge, while leaving the 2nd core after the endboss.
4. Similar to the cores, but way more impactful in the directly seen effects, an increase of one stat droped in each raid from Tikal to RofL or even DC, might be highly beneficial to the current gamestate. By increasing the amount of stats droped, people will be directly encouraged to run those Raids more often, which will make those stats easier to access and make the raids feel more rewarding. The higher amount of stats will drop prices in the aution house, making it easier for new players to buildup their gear, giving them access to further progression.
If your target is for more players to catch up to the current endgame, the old content should be easier to clear and progress through. Currently this is not the case, since newer players will have a hard time finding groups for necessary progression and the AC nerf might make this even more difficult then before. By lowering the amount of cores needed in RofL and the other 4 raids or atleast making them easier to collect by increasing their numbers, people will faster progress to dc and beyond.