Yes, and I watched many of my classmates take research years to do things exactly like I said above. People in my/our generation have this silly desire to "find themselves" and seem to think life should take a convenient pause while they do so. It's contributed tremendously to the rise in gap years as premeds and extra years as med students.
I feel this reasoning might be a little shaky. I have yet to meet a single premed tell me they are taking a gap year because they want to 'find themselves' or 'explore the world' or 'slow down' or any such screamingly 'millennial' thing. Anyone I've ever spoken to who has taken a gap year took it because they believed that their applications were incomplete or noncompetitive after three years of undergrad. I
might be inclined to believe you if the majority of pre-meds I had encountered in undergrad happened to be curious people with varied interests who place little worth in money and structure and time and more on their personal experience (indeed, from your description, you seem to imply a certain degree of narcissism involved with the notion of taking time for yourself, an implication RTC poked fun a). That is not the case. The vast majority of pre-meds I have met are neurotic, ends-justify-the-means, tunnel-visioning, structure-loving, risk-averse, money-and-time obsessed individuals. I am not saying that
not pursuing a gap year
necessarily means you are such an individual nor am I implying the converse to be true. I'm not making any positive claims. I am making the negative claim that your hypothesis does not line up with the pre-med personalities I have met.
If I were to put forth a slightly more plausible hypothesis, I would say that the 21st century undergrad is way, way, way too focused on extracurriculars. Although ECs are not radical, new things, the internet age has made group and event organizing easier, faster, and cheaper to do. Further, everyone and their mother wants to "start" something or be a founding member. The internet makes it easier to do that (since founding something just takes an internet connection, a facebook account, and a room reservation on campus) and the quest for "leadership positions" no matter how useless is a powerful motivator. Go to any college campus in this country and I guarantee you that 8 out of 10 undergraduates (not just premeds) spends more time worrying about, planning, and doing EC rather than academic activities. Premeds are even worse because of the pervasive and somewhat unfounded belief that the more involvement in ECs, the better. As a result, many people neglect their grades (unsurprising considering many premeds are hilariously dispassionate about anything having to do with academics), are too involved to have time to properly study for the MCAT and therefore put off the exam or end up taking it multiple times. Second, the cost of an undergraduate education has increased greatly in a relatively short amount of time. It is very normal for students to have to work a significant number of hours (15+) every week in order to curb or cover the cost of their education and living expenses. This was not necessary before and one of the major consequences is that people either take longer to complete all of their degree requirements much less the obvious expectations of medical school adcoms all over the country (research, clinical experience, service). Sure, some can juggle it all without too much issue or are exceptions to the rule but if you want to keep a strong GPA, work enough to pay your living expenses, and build a competitive application then the smart thing to do is take more time and do it properly, not to take less time and sabotage your grades or health in the process.
In general, I don't think wishy-washy and airy ideas like "finding yourself" and wanting to see the world are powerful enough motivators to explain large trends. The two biggest reasons people take gap years, I would posit, are that they either do not feel prepared to apply or would like to make themselves more competitive in an increasingly competitive field.