Why would it be the only option? It seems to be the standard in Europe, but not sure why you couldn’t connect it to the hot water line instead. This is especially true if you have an efficient hot water source like solar or a heat pump water heater.
You have to hire (or be) a plumber to make the change. Often getting access to the pipes can be tricky. Depends on how your house is though. Sometimes this is as simple as connecting the hose to the other valve already in place, sometimes this means opening up the wall to get access to the pipes.
Normally the only pipe that's available to dishwashers is the cold water pipe.
However, even if you had hot water available, it would actually be to hot. The hot water entering can be much hotter than the required 30C for the lowest setting, so the dishwasher would need to cool the water.
In the U.S. dishwashers are almost always installed directly next to the kitchen sink, where either the cold or hot line can be easily tapped with a tee valve. I guess plumbing/kitchen layout is done differently in Europe.
As for heat setting, what’s the reason to be concerned with tap water being too hot? I don’t think plumbing code would allow water to be available at the tap that was hot enough to actually damage any type of utensil/drinkware/etc? I presume the only reason there might be a lower heat setting is simply for energy savings, which is kind of moot if you’re instead pulling hot water from the efficiently heated water supply.