Dipping down was definitely meant to be special even then.
It just feels like some of the very early boarders may not have though much about Star's regular magic and the seemingly limitless power she had, just having her spam incredible magic soon after getting the wand. With the second season establishing she makes 98% of spells up (this was suspected early on but not really proven), basically skipped over basic stuff straight into advanced but is thus incapable of some specific tasks, and has traits of a more powerful ancestor, sort of balancing out and accounting for her skill. The focus on how she doesn't read her spellbook also explains why it didn't show up much before-- obviously based off her established character traits, but not really shown on screen before then.
A "spades" character must have been planned when they decided on the card suit motif and Miss Heinous being clubs; I just don't know if they'd thought of the exact details of Eclipsa at the time.
Though it's not like I'm downplaying the writers' role in this. It's just that two has had a fairly consistent story team while in the first season different people would write the outlines for different episodes, and for about half the season it seemed like everyone was content with it (or felt it had to be) just a shallow comedy.
By the time Toffee showed up obviously they'd started to have greater ideas about where to go from there. The impact Storm the Castle had on the next season's plot was pretty clearly thought out well in advance, compared to things like the finer details of magic.
It just feels like the early executives who left in the first season might have held things back a bit, and some writers were more concerned with plot/lore than others (the same guy is involved with almost all the major "monster" plot episodes in the first season)/