If you look at the beginning of XX century, university education was much less accessible with much fewer participants, and the results were much more impressive than today across all disciplines
There was also a lot of relatively low-hanging fruit in most fields, because we basically didn't have the technology before, or simply didn't bother to look.
There's a ton of low hanging fruit now - more than ever. Every question answered raises multiple new questions. If there is a lack of opportunity to answer interesting questions, it is certainly not because the questions aren't there.
But someone needed to realise it's a low-hanging fruit in the first place. By the end of the XIX century the general agreement was that physics was pretty much done, we are now just polishing the details.