Suggestion for: RDM improvements

[Archwizard]

Sure. Why not? Use Displacement if you want to or need to for movement, use Engagement if you want to or need to for mechanics. There shouldn't be a 50 potency penalty because you have to stay in melee range due to platform sizes (I'm thinking E3 and Suzaku) or because you need to stay with the party for stack mechanics or healing, or if you can't leave the area. There's no reason that there should be a difference in potency for those who either choose to stay closer or for time when you must stay closer.

The problem with that is that Displacement isn't DRG's Elusive Jump. It's an instant damage CD, which shares a charge with a damage CD -- and maximum damage from instant CDs will come from using them as soon as they become active, unless they have A) charges so you have an entire CD's leeway on timing or B) mechanics that increase their potency for holding them for an ideal circumstance (which due to them both being physical damage, we don't get from any other abilities). The current disparity between Displacement and Engagement is an ill-fated attempt to induce scenario B.

If Engagement did equal damage to Displacement (or at least near enough as to be inconsequential) and no other changes were made, the only time you would pop Displacement is if it came off cooldown at the EXACT SECOND the boss dropped an AoE marker in the melee -- otherwise, it will never even be available because you'll be using Engagement on CD, especially with your suggestion to make auto-attacks stronger for RDM since you will want to actively avoid jumping backward for the whole 10 sec to greed out maximum damage.
(And bear in mind, the theoretical scenario you suggest where Displacement remains objectively better has to exist in the same realm where current melee jobs are not at a significant disadvantage for lacking similar escape tools. Which only DRG has.)

There would be no "use Displacement when you need to," or at least not with enough frequency to justify it being a separate ability. Displacement may as well be taken off the bar in such a case.