As others have already stated on this thread, you need to bring back the previous alert system or at least something very similar to it. I also understand that you (DE) introduced the nightwave feature to to give us players a reason to continue playing. As such I think it would be a good idea to do the following:
1: Have the nightwave rewards be currently available relics, formas/umbral formas, and wolf credits.
2: The wolf credits could then be used to purchase warframe part schematics (not the prime variants, which are obtained from relics, just the regular versions) and cosmetic items like warframe helmet schematics and weapon skins.
3: Everything else, including Orokin Catalysts and Reactors, must be made available with out having to grind for 3 to 4 weeks on a set schedule. Most preferably having those items awarded to the player upon completing the mission/alert that is giving them.
4: Increase the amount of nightwave challenges available so that there will be something for the both the dedicated players, those who like endurance runs etc, and the casual players. This will ensure both groups can enjoy the content at their own pace with out ruining the others experience.