Like every other event, this one should include a few basic QoL items including... Persistent vendors even when event not active. Listed in activities (Ctl+G) when event active. Travel to event / quick travel points within event.

For the crew skills issue, just remove 'Onslaught Crafting' (set max crew skill to 700 for everyone and remove the skill from trainers), then run an update that checks actual crew skill, and if equal to or greater than 600, sets actual to 700. Either that or just come out and say the 'bug' was allowing people to access 700 without buying the 'Onslaught Crafting' , re-impose the fee, and set every crew skill for which the training has not been purchased back to 600. At this point, I've already bought the skills on multiple characters - both back when it was required, and now because of the incompetence your team has shown in fixing the issue (I don't have months to wait while you keep screwing up the fix by not actually fixing anything such that my characters cannot use crew skills above 600 they previous could access). So just stop trying to fix it while trying to re-impose the fee - remove 'Onslaught Crafting', set everyone at or above 600 to 700, and move on. All your current efforts are just a giant waste of time - both of yours and ours.

If most issues with Nightlife only occur after a period of time post restart / new instance, how about spawning up more instances regularly, and possibly restarting NS as a whole at least once a day (set a time and communicate)?

The only thing that was off about the 4.0 gearing system was the HM of the week providing better gear than NiM. To say such a flaw makes it the worst gearing system ever is, well I don't even know what to call such silliness or idiocy. Not to mention if you were bothered by people getting top gear doing the HM of the week, players getting the best gear in 5.0 by winning the RNG box lottery after grinding to 300 farming pigs in KP, or getting the best gear in 6.0 by spamming HS over and over must really set you off. So how is 4.0 worse than what we have today?