The old event form allowed you to limit the number of registrations per registration option. This is highly desirable, for example, when I provide a free staff or student option but allow people to buy additional tickets, I don't want registrants to be able to register more than one person for those options.
This was possible with the old event form, but not the new one. Instead, the new form limits the total number of registrations allowed, which isn't useful at all.
This idea is currently in development with a planned release date of SP19 - January 2019.