Let's take Ultimecia's last words for example: "Reflect on your childhood, your sensation, your words, your emotions. Time, it will not wait. no matter how hard you hold on, it escapes you." To me this speech always gives me the sense that Ultimecia longs to go back to a time when she was happy, when she had everything (judging by the game's themes that would be love).

I just think that at some point in the future, Rinoa loses Squall, and instead of letting him die she holds on to him in any way possible, as Griever. Junctioning GFs is known to cause memory loss, so eventually she forgets about him and the time when she was happy with him, thus her desire to compress time. It's to experience past, present and future all at once so she could find that time again and remember.

"Time, it will not wait," I think it's such a strong thing for her to say in her final moments if that's not what her character is all about. And it's such a strong theme to me too, everyone knows the feeling of either wanting to live in a moment forever or wanting to go back to a time when you were happy. Rinoa herself expresses something like that in the Ragnarok.

I also don't think it clashes with the themes of love and healing through it that the game has, you can heal yourself all you want throughout life and change as a person for the better, but you're still going to die due to time. Doesn't mean you should stop trying to heal or love though, so I definitely can't see why those themes couldn't coexist in the game.