Kirby is what it is. I think the thing about Star Allies is that it is still very much familiar in terms of identity to the franchise. I'm not chastising anyone for not knowing but this can simply be an age thing. I've played Kirby when I was little on the Super Nintendo where you could play multiplayer on the same screen while riding the hamster. Generally you can expect Star Allies to still have ultimately the same gameplay and similar difficulty. Pretty easy throughout. The main demographic is aimed at kids. This doesn't stop adults from liking Kirby. It's cute, it's cuddly, and your special power is not limited to one unique power but ALL of your enemies powers.
The game is interesting but the actual gameplay is not for everyone.
Whereas Octopath Traveller IMO will actually appeal to far more people. Turn-based RPG games have been in gaming for a long time. They represent some of the most iconic gaming franchises in history; Pokemon, Final Fantasy, or even a cult game that's as recent as Undertale. It's easy for people to like turn-based RPG because mainly they need to fall in love with the characters/story/plot/setting or the gameplay.
Octopath literally looks like a remastered version of the older Final Fantasy games with far deeper polish and SO FAR (inconclusive as I've only played the demo) the story is not quite as cheesy/melodramatic and over-the-top as it usually is with many JRPG games. I think the stories of the two characters in the demo were great even if a bit predictable for the introduction.
I'm in the same boat. Octopath will likely be a Day 1 or first week purchase. Kirby I'll only probably play around with the demo. As said before, Kirby while being a casual game anyone can pick up really is for specific players/gamers. Octopath will actually appeal to a much larger and wider audience. I think a lot of people have been waiting for a very deep turn based JRPG again.
The last turn based games I played other than Octopath were Pokemon (which honestly is kind of in its own genre rather than competing with other turned based game), Undertale, and Monster hunter Stories. They were all very good; Pokemon is always good IMO and Undertale was very good. undertale even had a good story but they all lack the depth of plot I want in RPG games like this; which I believe Octopath will fulfill very well.