Gee, I didn't have one for my OW classes and neither did anyone else in my class. Yes, everyone does need a depth guage but if you are all going down with the instructor for a pre-ordained amount of time in an OW class, it is just BS nickel and diming the customer to tell them it is required in that class.
After an OW class, yes, you do need a timing device.
Perhaps that title of this thread should be changed from "Cheap Bastard Divers" to "We'll Screw You If We Can, LDS'"
That's great if you want to train people that SOMEONE ELSE is responsible for tracking their dive time, but what happens the first time that someone dives without an instructor and wonders "Who's gonna track the time for me?" By your assertion there's no need for the student diver to carry an alt reg, since the instructor will have one. No need to carry a depth gauge, since the instructor will have one. No need to carry any cutting instruments, since the instructor will have one. No need to have dive tables, since the instructor will have one. Heck, no need to plan the dives since the instructor will do that.
Training someone to be an autonomous diver who can plan, execute, and properly log OW dives (especially critical for planning and executing repetitive dives) on their own WITHOUT requiring them to actually do that in training - including having gear appropriate to the task - is foolhardy!
I'm not saying you need to buy some expensive bottom timer either. It's not about selling more gear. Any cheap plastic $19 watch that can survive the planned depth is fine. But without a timing device you are not appropriately geared for an OW dive.