Indeed... it's not that expensive knives aren't absolutely wonderful. Many certainly are.
For me, it's just that my purposes are simple and un-demanding; and I'm just not motivated to spend a lot of money on a knife. (Guitars and cars are another matter!) And some nicely made inexpensive knives serve my typical uses (opening packages on a daily basis) very well.
I guess priorities is what it's all about. I happily spend $1000 on components to build a great Fender Telecaster from premium components, and have done so numerous times. (Creating music is at the center of my life.)
But when it comes to knives... I'm not motivated to spend more than around $100-ish at most - and typically not more than around $40 to $80. For my simple needs, I enjoy using the $25 CRKT Folts Minimalist Wharncliffe immensely. Awesome little knife! It needs sharpening more often than some, of course, but is quick and easy to sharpen. And... I'm only opening packages with it.
I'm the same with firearms and flashlights, as well. I tend to use my less "fancy", less "costly" ones more often than my fancy ones (M&P40 or Glock 30 vs. Custom-grade 1911's, for example. Or Zebralight & EagleTac vs. Surefire). Not sure why, but it just is - the "everyman" models are the ones I tend to grab, and carry daily. My daily carry lately has been the M&P40 Compact, EagleTac D25A, and Cold Steel Mini Tuff Wharncliffe - all pretty much "everyman" products.