Modern-Day Tech is far more fun. There's tons of technology to use (the internet, cars, computers, etc) and you don't have to be restricted to a fairly limited set of morals (1500s-1600 people were not exactly known for trying to be individuals).
1. The technology level of a conculture has absolutely nothing to do with that culture's morals. You don't need to make your people seem like they're fresh out of the Dung Ages just because they don't have electricity.
2. Part of the fun of conworlding is making a place that's vastly different from our own. How did friends talk to each other before the dawn of the cell phone? The answer is not
"they didn't." Including gaps means you have to create interesting ways for people to work around these gaps.
3. Finally, there's the avenue of alternative solutions
to the problems that modern-day technology was invented to solve. What if we invented the airplane before the automobile and everyone flew to work everyday in little biplanes? What if love potions actually worked and nobody needed dating sites anymore?
I can't really understand why 99% of all conworlders suck Mediviel Europe's dick so much.
The ones who think civilization comes in 4 forms: Modern Day, Medieval Europe, Ancient Rome/Greece (they're indistinguishable), and Cannibalistic Barbarians. They're blind to the possibilities.