Having Confiteor replace Requiescat might be a convenient change for some, but if you're someone like me who mashes skills to combat high game latency, you might accidentally end up using Confiteor right away.
Also, if 6.0 adds a second ability able to be used in Requiescat, like a higher potency, single target option equivalent to Xenoglossy, then that change wouldn't be as good.

It all comes down to what the devs have planned. Some things may already be planned, some may be unnecessary due to changes we don't know about yet.