I'm lucky that despite living in a car centric Texas suburb, there are tons of of bike paths, and quiet neighborhood streets to get a workout ride on. Commuting by bike is currently not viable, but a new commuter rail line is opening next year that might make it work for me.

And also not wanting to show up at work a sweaty, disgusting mess because you decided to do threshold intervals on the way to work

Although i've been told that it's normal for dutch people to show up at work meetings in various states of wetness like rain or sweat

right but it's comparable to the type of cycling that the grand majority of people do on the bikes at gyms

which, to be fair, is often because that's a warmup/cooldown activity at the gym. but there are people who go and just cycle at a low moderate pace and then drive home.

If you're fit, then cycling will ensure you stay fit. If you don't have to strain yourself, that's a plus. It's supposed to be fun commute, not a challenge.

If you want to workout, go the long way?

Indoor biking isn't much of a workout either to be fair.

It's one of those things that seeped into the public mind as part of going to the gym. Whereas you can get the same or better cardio while lifting weights that also builds your muscles, while indoor bike is imo just a meh, or borderline the "lazy" choice realistically for a lot of people.

It's what you do when you don't want to run because that's hard, and the elliptical is too hard because that actually hits the whole body.

Ofc this is a generalization of the majority, individuals can still use it to great effect, but imo, meh.