I know that some people party all night long, but even in college, even when we had no restrictions (i.e. house party) things were mostly done by 3 am. Yes, there were occasional later nights, and yes, some people have schedules that make the wee hours of the morning a perfectly sensible time to have a beer, but is there really enough of a pool of patrons to have bars stay open until 4 am? Well, in a working/residential city anyway (not Vegas, not New Orleans)?
I know I'm old and all, but things just go downhill fast after 2 am. Also, nearby residents probably will hate it and stay off my lawn (don't really have to worry much in my inner burb hood).