You are right, with 20+ episodes it’s easier to have a common theme while still being episodic enough to have episodes that don’t advance the plot but are either funny or explore some unrelated theme. 10 episodes season work for a serialized series (like discovery), but an episodic 10 episodes series is a hybrid of the two and more difficult to pull throught.

However, I still think they did a good job, the season was fun and enjoyable, and I don’t really care there’s no “big picture plot”. After all, this is not telling the voyage of a ship lost in the galaxy or a multi-year war with a foreign dominion, it’s a character build-up story that will eventually become the original series, it’s a prequel and doesn’t try to be anything else. Surely I enjoyed it more than galaxy-destroying-threat-of-the-year discovery.