I heard some people complaining about this on a podcast but my view is that they're doing a good job alternating between the heavier episodes and the more lighthearted episodes. If we had 5 light hearted followed by 5 heavy episodes, it would be more jarring than alternating as they have been.
This is the episodic show for which the fans have been begging for years. Now that we have it and get the fun episodes mixed with the harder hitting episodes, some people have complaints.
We also have to consider that they are getting 10 episodes instead of 26 or 22. You're not getting 8 good episodes, 8 meh episodes, and 6 bad episodes anymore (thos is a reference to how screenwriters viewed episodes at the time). Now we have 10 episodes that need to be on point with maybe a couple meh episodes.
In my opinion, the best way to do that is to alternate as they have. Not everyone wants a serious episode every week (like all those complaining that Star Trek has become too dark) and not everyone likes the silly episodes (as referenced by those who didn't like the crossover). By alternating, you get that old school Trek, episodic story telling that make Trek so great to begin with.
I know you weren't saying all those things I'm alluding to but I was talking to my radio in the car as they were saying these things today and your comment brought those thoughts back out.
I mean, I keep thinking back to all the silly episodes of TNG, DS9, and VOY. Personally they are some of my favorites and don't detract from the more serious episodes at all.