So many people here are just missing the point completely. This is lazy balance design on DE's end, and a complete anti-consumer practice. DE knows players will keep buying/acquiring more plat to get better and better stats for their favorite weapons. They would/should be spending their time buffing less popular/weaker weapon rivens to give us more variety for late game content, not FORCING people into looking at what else they can use. They can't rework base stats too crazy because there has to be weapon progression in the game to give newer players a sense of power creep. Rivens are what allows those weaker weapons that people love a chance to become viable for late game content.
This is flat out scummy EA crap and I really hope player backlash kicks them in the butt for these nerfs over the last few months. Anyone who bought platinum to purchase Rivens that got nerfed just lost a crap ton of goodwill for your company. Anyone who invested time and effort to acquire platinum to get good rivens that were nerfed likely lost just as much goodwill also.
DE is like an abusive spouse, you love them and don't want to leave them.. but every once and a while they get drunk and beat you senseless for no damn reason. Anyone defending DE here is doing so out of fanboyism or personal bias against rivens because they cannot afford them or don't have the time to acquire them and roll them.
One day DE, you're going to lose faith from your players and we will be looking for other live service games to play that won't punish players for using weapons they love to use. Destiny 2 is coming to Steam pretty soon and if that game even gives me half of the enjoyment Warframe does I'll be taking yet another long vacation away from this game.
I will not idly stand by and support these types of changes to Warframe. It's hurting the playerbase and the game even more than ever.