@Yggranya To be fair, Phantasy Star Online 2 is a relatively large series in Japan that extends beyond just "Phantasy Star Online 2" when you take into account the merchandising, the live events (and live concerts that some had livestreaming for), the side-stories (PSO2es, IDOLA Phantasy Star Saga, Phantasy Star Nova, and now New Genesis), and some of the other media (Episode 0 manga, two anime installments, a trading card game, and crossovers/cameos with other games).
On the global side we barely got any of that but I would hope that Sega considers bringing more of that over to the global side at least in the form of something like livestreaming ARKS concerts (Like this ARKS Dance Festival)
The main one I miss is Our Fighting, since that was more of a rock/guitar-driven song with string accompaniment. Which I think is fantastic.
I really wish we could have had some of the other concerts (like the Sachiko Koyabashi conert) and especially the nifty decorations involved with Our Fighting. In that version of "Our Fighting" I linked you can collect the items as decorations for your Personal Quarters and then simply play out the song. If you can invite people to take the role of other instruments or vocals, you can literally turn on/off parts of the song as the players end up recreating the song. Every version of the song you end up playing will end up having some kind of variance in it as even the official soundtrack version of this particular song is distinctly different.
I do think if they intend to continue with concerts I would absolutely love to see more crossovers and variety in musical genres or at least that we could have had some appearances from others such as Matoi who performed live with Quna (Album Promotional Video / Cosmic Twinkle Star Live). In the global version, the closest you got to this was Quna and Matoi's version of Rare Drop☆KOI☆KOI which showed up as one of the Christmas event songs. If you look around you might find the actual concert up somewhere (it was archived from a livestream but otherwise is via an officially-released BluRay).