With the way lilies are set to work, as they passively generate every 30s, then it would functionally change nearly nothing if the way they worked was just that:
Once you have a lily, your next Medica or Cure II cast cost zero mp and was instant, and consuming the black lily still nourishes the blood lily.
Why even bother making Solace and Rapture buttons? It adds unnecessary button bloat, adds literally nothing to the class except unneeded complexity.
And I'm not against WHM complexity, it's just this is, well, half-assed. It's skills we already have - duplicated. Why not give us something new? Like some much needed raid utility...
The ONLY thing having the extra buttons do is for some reason allow players to sit on a lily while casting a standard cure II or medica. To what end? You already so seldom cast both of these skills, instead relying on regen/cure3/oGCDs for better play, so it's not like you had to worry about which of your 30 cure2 casts you'd replace when you can probably count the number of cure2 casts on one hand in an 8 minute fight. And if you think this should accommodate for players who do cast cure2 that often, then both you and the mechanic design are encouraging awful play. Why not design something that more intuitively encourages proper play without adding complexity? AST's malefic cast time was a good example of that, you can now weave after every malefic cast, and even players who have zero idea what weaving is are still functionally playing better without even realizing it.
The game's pacing is so slow you don't ever need "instant emergency buttons" either -- if you do, you're just not paying attention to your screen.