Don't get me wrong, if you have a good jam or preserves it's totally fine on a sandwich, and I wouldn't turn my nose up at it. However, peanut butter doesn't really need the help, and the extra sweetness from jelly is totally unnecessary. Toasted bread and peanut butter is all you need for a quality simple sandwich.
You understand we have real PB in the states, too, right? The fact that you chose to buy crap in the states does not reflect poorly on us. The PB I buy is not sweetened.
That would be like me going to Vietnam, trying pho with tripe, and concluding that all pho in Vietnam has tripe.