Your logic has a few flaws. Boilded down, you postulate: If the machine can write index marks, it should be able to read them as well (and also allow use of that). That's fine in a wishful thinking world, but certainly doesn't follow the business model approach: you get what you paid for.
You apparantly think all the features of "upper level" devices should be included on lower-end devices as well. BUT, what's the purpose of even having multiple models, and upper and lower end models?
If your thinking was true, people would quickly learn that If I can get ALL the features of an upper end model on a lower priced unit, why bother to pay the extra? No one would bother buying the upper end models.
How about: they didn't bother deleting the index writing capability on the lower-end model, so you actually got a BONUS in that your other upper end JVC models can actually use them? They just didn't happen to think that It was neccessary to delete that festure, since they already deleted the reading capability. As I see it, you actually got more than you paid for.
If you wanted another JVC with "reading" ability, then you should have paid the extra bucks to get a model that supported it. I'd say you didn't do your homework first and check out just what features the vcr had, so I'd call that bad planning. Blaming JVC for your mistakes isn't fair to JVC. No one forced you to buy a cheaper model expecting upper-model features. Now, if JVC advertised and claimed it had index reading features on that model and it didn't, then you'd have a legitimate complaint, and grounds for action. If they didn't even mention the index writing feature that it does have, you got more than you paid for.