I agree with you. I'd love to try a 4k screen, and was even considering it - however in the end I took my home U3415W to work and bought the X34 for home (I might game 30 minutes a week or something; the extra hz are certainly nice for that, otherwise they are pretty much identical).
I value actual real estate over PPI, preferring to run at 100% / unscaled which looks much nicer in Win10. The 109PPI (3440x1440) is decent enough, and I don't have to squint. Furthermore the DPI matches those of the surrounding 16:10 24s (1920x1200) well enough for it not to be an issue.
I am trying not to cargo cult here but I think if I need to scroll a file with 9 font on a 32"+ screen with 4k display it might be a sign of code smell (again, this should definitely not be a hard rule just saying it might be nice to stop and think why it is so long)?
I value actual real estate over PPI, preferring to run at 100% / unscaled which looks much nicer in Win10. The 109PPI (3440x1440) is decent enough, and I don't have to squint. Furthermore the DPI matches those of the surrounding 16:10 24s (1920x1200) well enough for it not to be an issue.