Way back in the day, in the small town in Ireland I grew up in, reserved seating was the only kind of seating. It almost seemed like an excuse to hire extra people, so they could check your ticket and show you to your seat. Then, when the multiplex came in, revenue maximization was the goal, and reserved seating went away; probably helped with ad impressions too. Now, in London where I live, if I want to reserve a seat, I need to pay extra (e.g. VIP ticket in Vue cinemas), and get a marginally larger seat etc. (though still, no-one shows you to your seat unless it's a really big feature).
