Gravity was never really that difficult to land on difficult content anyways... Very Difficult is another story though, where Meva on mobs can be stupid high for ALL spells and a total pain to land without Stymie or Elemental Seal.

The problem with taking away Gravity's evasion down effect is that you lose a spell that could possibly land more easily than Distract on certain monsters (fire based, especially). And yes, this was effectively a nerf to Rdm because their Gravity II's -25 Evasion was nice enough to be noticeable and worthwhile, and Rdm needs all the love it can get right now. It's more of a slap to a face because we weren't told of this until the update actually hit. This was also a small nerf to MR and Rudra's (yes! my Brd is sour over this), where the Gravity was always a nice extra boon to essentially be able to give Acc+10 to your entire party through WSing and applying Gravity at the same time.

Also, you didn't need Enfeebling potency gear to enhance Gravity's Evasion down effect; it was static and doesn't depend on any dStat or potency gear. You need it however for Distract if you want to improve its potency, and for Rdm on harder content, this can pose to be a problem because they lose so much Macc from switching out their Body/Hands/Feet slots for these types of pieces that enhance Enfeebling magic. The Dev team really needs to push out reforged Emp armor already to help resolve this. And/or they should give Saboteur a significant Macc boost; that would help Rdm out immensely.

Finally, Gravity's evasion down effect would have stacked with Distract. So for Rdm, I don't see how you can't call this a nerf by them removing Rdm's Gravity II evasion down.