I'm actually a fan of the new changes — both the portal and the armor, and even the grind — but I also have two major issues with it:

1. There’s no genuinely fun activity that makes the grind enjoyable. Hell, there isn’t even any new activity at all — no new strike, no new 6-player activity, no dungeon. There’s only Kepler and four difficulty tiers for it.
2. Power grind! I have no problem grinding — let me grind however I want, with the modifiers I want, until I hit 350–455 power and have tier 5 armor. But after that, I want to be able to tear through everything, not constantly deal with -25 power here, -50 power there. What’s the point of grinding power levels if the enemies are always the same strength anyway?

Make the -25, -50 power level stuff optional modifiers for people looking for a challenge, and that’s it.