I think part of the reason why devs show off things like particles and animations is that it's the easiest and flashiest thing they can show off. This kind of stuff is usually called "game feel", I believe, and it is something that games are definitely using more and more of. Even something as limited as a visual novel uses a lot of effects during dialogues to add oomph where it needs to be. This even goes back to something as old as the sound of scoring a super effective hit in Pokémon vs a normally effective attack.

I actually had a complaint about this myself during testing, that it felt like some of the attack animations dragged out too long, which dampened the feel of performing an attack. These things such as visual flairs, sound effects and even the pacing of attacks are small things that can nonetheless really change how satisfying it feels to do things in video games.

I think almost everybody appreciates a game more when the actions they perform have the proper sense of weight that they should. MARDEK would be a lot less satisfying if every attack just used the same generic hit sound and SFX rather than a distinct sound effect and SFX depending on the skill.

I like the particle effects!!

I actually did play an indie RPG recently, and it used a lot of the same stock sounds as MARDEK! That was always amusing, since the game is very definitely in the 18+ for sexual content category, so hearing these sound effects I associate with MARDEK used in this game made for a funny sort of discord.

Hypomania!! That's almost close to Mania. You're becoming more like me every day, yes!!