If you had to ask me, Smash should push a lot for picks such as Terry, Hero or Joker while keeping a certain amount of interest towards fan demand.
Smash is indeed a game that overall assembles many of our favourite series... but wouldn’t it make sense for the Smash team to also showcase picks from games they played but don’t get enough love from the fans overall? Sakurai added Joker both because of Atlus’ relationship with Nintendo and personal love for the series which he wanted to motivate some of his fans to experience, Hero was added since both the Smash team, Nintendo and Square wanted the western market to give more value to DQ as a series so people could get contact with stuff even Sakurai personally admires due to the impact DQ had on his country, all while adding some fanservice to the Western DQ fandom; Terry is an icon from the series that basically inspired Sakurai to make Smash, so of course Sakurai could want to give his series more widespread attention so it gets more reputation. Hell, even back in Melee we had additions such as these through Marth and Roy, who were added in hopes of growing interest towards Fire Emblem in the West.
And sure, I may be one who would deeply love to see Crash Bandicoot sharing screen with Eight and Samus on official media.... but at the same time I love to see Smash getting me invested on series such as KoF, Persona or even Metroid back when I knew nothing about videogames in general outside of a casual point of view.
Is it fine to please the fans... but it is also a great choice to add picks that could give underrated series the love they deserve.