I always found it weird that RDM is better at reviving people than an actual healer with a kit that clearly has Swiftcast baked into it. I don't think RDM should be changed at all tho. Mechanically I like the way the class plays. Instead, I think healers should be prioritized for reviving party members by changing two things.

First, I would alter how 'Weakness' is applied by making it a debuff received from DPS Casters only. The usual 25% for the first death and 50% for the second would still be there like we have now. Healers would instead cause a debuff called 'Fatigue' which would apply a 10% reduction in stats that grows by 10% each time a person is revived to a maximum of 30% after the third revival. I would make 'Fatigue' and 'Weakness' stacking Debuffs so that both could apply simultaneously too. This would make a player benefit more from a healer revive since 'Fatigue' is the lesser punishment. The option to help as a Caster would still exist but healers would definitely bare the primary responsibility. This shift in importance would be a great opportunity to reduce the Rez tax placed on SMN and RDM.

My second change is to reduce the baseline cast time on Revive for all Healers to 3 seconds. This cast time would increase by 1 second for each revive a healer casts while in battle as a permanent stacking penalty up to a maximum of 8 seconds. This would mean it would take a healer casting revive 5 times to reach the 8 second cast time we have now.

These changes would make reviving party members a more tactical decision. They would also support removing the Rez tax from casters and add relevance to healers who have had their responsibilities shaved down to almost nothing in recent expansions.