Overall, I like the idea of Nightwave. Little mini challenges that you pretty much can get easily every week just by playing, and then a few elite challenges that push you to do things you wouldn't normally do. My friends and I had great fun with the elite challenges.
Let's be honest here. Killing 150 enemies with an energy type or weapon type is not a "challenge". Just switch up the mods or use only your melee/secondary/primary for a mission or two and you're done. Conservation, fishing or mining gems? Again not really a challenge, just a bit of time out of your schedule but we're talking 10-20 mins. Run 3/6/9 missions of a type? I did those as void fissures and cracked relics. Generally this is part of regular daily/weekly play and not an inconvenience.
Yes, some of the other challenges can use some tweaking. But DE was pretty up front they wanted feedback on that.
ie: Filling 5 ayatans just increases the price of unfilled ayatans 10-15 plat each. For newer players, the only guaranteed ayatan a week is from Maroo's quest. But if it was a seasonal challenge, fill 5 before the end of the season, anyone could reasonably achieve that without spending plat.
ie: Having 3 challenges in the same week to run a 60 min mission is a HUGE time sink. One a week isn't bad, or in the case of the 60 min survival and 60 min Kuva without using life support that can be done in the same mission isn't as bad. These are Elite missions, so it's okay if not everyone can do them or wants to spend the time.
Ultimately, if you weren't grinding alerts back when they were alerts, no one says you have to grind Nightwave. You probably have everything that is offered to buy with wolf creds anyway. If you're after that umbra forma, well those were never part of the alert system.So if we were to drop Nightwave, you aren't really getting them any easier. I thought it was a nice little reward for those who put the time in.
I look forward to where future Nightwaves take us, and the journey of tweaking the system along the way.