It’s funny that OP thinks reading romance has made them a less critical reader, while everyone in the comments says the opposite. I also fall in the camp of being a more critical reader than I was before I started reading it around 2014ish. Like the commenters noted, having a predictable story structure helped me both learn structure and more critically consider the aspects of the specific book I’m reading because I have a mental framework to compare it with. It adds another level to the reading experience for me (others may get this from different genres, but I don’t usually). It is a little hard to disentangle how much of this change comes from reading romance and how much from writing, because I’ve also concentrated on learning storytelling in recent years.
It’s definitely true that romance is a faster read than other genres — but I think that actually matches my preferred style of reading. I’ve always been a fast reader, in both speed and jumping-ahead / skimming — I get impatient and want to get to the action. Beautiful wordcraft doesn’t do a whole lot for me (I’m more into style), and complex metaphors usually go over my head 🤷♀️ Poems and songs irritate me. Deep, moving tragedies piss me off. The things that others get out of literary books are not rewarding for me — while romance delivers books that are more my style in both pacing and substance.
Finishing books faster, I also read way more of them. I jumped from reading an average of 50 books a year in 2009-2013 to 115 books a year in 2014-2017, then up to 175 books a year in 2018-2021. Taking in a greater volume of stories also helps with learning story structure — having a larger sample size makes patterns clearer.