While I don't think that they barely take anything seriously in this series, I do agree that Rowlet falling asleep would have been treated as a problem in any other series. Even Ash in the original series recognized that Cyndaquil taking too long to be ready for battle would put them at a disadvantage. I have wondered multiple times why Ash even caught it. Granted, I don't think it would have fit with any of the other cast members. It might have worked for Mallow if she was interested in Grass type Pokemon, but even that feels like a bit of a stretch.

As for the question at hand, Rowlet is the most popular Alola starter, so that gives Ash's Rowlet an edge in terms of popularity. It's cute and its sleeping gag can also be considered funny/cute. I did like the gag for awhile, but I became annoyed with it when Rowlet couldn't even fly over a small hill to get a berry right in front of its face. That's when it stopped being funny and became a serious problem to me. Like I mentioned before, I've wondered why Ash got it when the bulk of its screentime throughout the series has been sleeping. I'm aware that it's getting more screentime/focus in more recent episodes, but does that really make up for it being a one note gag Pokemon with barely any presence for over a hundred episodes? I doubt it. Maybe it will be different once the dub gets to this point, but it already gives me the impression that the writers are just playing catch up because they had Rowlet spend too much time just being a gag Pokemon and now having to make it useable for the upcoming Alola League.

Oddly enough, I don't really mind Rowlet getting an Everstone. I don't think it was given for fanservice so much as just confirming that Rowlet won't evolve. As much as people wanted to see Ash with a Decidueye, there wouldn't be enough time for Rowlet to fully evolve without feeling rushed or forced. I think that there was a bit of backlash when that episode first aired, but considering that Rowlet spent so much of the series sleeping in Ash's backpack, it might as well not evolve.