Practically speaking, I think Elise is supposed to kiss Sonic. It wasn't just because she loved Sonic. You can't swap Elise out with another and expect it to be narratively functional. Elise has a unique power. This scene is "Solaris" (the sun, who Sonic thematically is).
I said that last part mostly to grab your attention, but I'm serious. It is all parallel. First, know that the Secret of the Flames specifically relates to Elise (the vessel) and the chaos emeralds. If it wasn't evident before, Eggman (for example) repeatedly spells it out.
The Solaris prototype scene... Notice how he needed a chaos emerald to demonstrate-start it. The same one he earlier said will be his to Sonic — the one he vowed to get back later.
The Egg Carrier crash scene...
Elise's first kidnapping scene...
The beginning cinematic....
The Last Story...
The sealing of Iblis scenes...
It's made abundantly clear that Elise and the emeralds are catching-holding, sealing, and/or binding agents. Hence Silver's words. "Sealed with a kiss." A kiss is a metaphorical seal. Elise is catching Sonic's spirit and sealing it back in him with the power of miracle.
Also remember how Chaos Emeralds function, as well. Power comes from the heart.
This time around, it is of love (Sonic) rather than hate. Hope (what Solaris once was) rather than despair. The act of sealing Iblis was out of control and constraint. It was sealed away to prevent union. The act of "sealing" Sonic was the opposite.
Additionally, Elise has a "hidden power."
Not lost on me how whe Solaris is defeated in past, present, and future — the two people drawn to the past and its beginning is Sonic (who seems aware of what you would think he wouldn't be) and Elise.
"I am... The sun."
Sonic is also the sun.
You don't have to like it (I do not ship Sonic and Elise), but there was actual utility to the kiss. It wasn't just because and random. You cannot just replace Elise with some other character you want kissing on Sonic and it working the same way. 😂
@guessingdame You can consider it mouth-to-mouth resuscitation. Because it is.
@guessingdame What bout having both Elise and Amy both do it? That way Elise still uses her powers to bring Sonic’s spirit back, but Amy makes Elise’s ritual to revive Sonic even stronger with her own love for Sonic.