If something is considered niche, there is no need to remove it. Just don't put it on your bars. Repose and Sleep should stay. Fluid Aura as a damaging ability could work, but what we have now has its own admittedly limited use for moving mobs.

Combining very dissimilar skills also seems like a bad idea. Looking only at PLD, Bulwark and Tempered Will being combined means you lose KB protection if you need to block and vice versa. Placing FoF and Req together leads to a similar issue. FoF lasts much longer, if something like a phase change in coming up you might want to Req but not FoF.

If there is any button merging it should be optional. Nothing should be outright removed.