Plastic and aluminum roller shutters

It definitely stands out. It would be an absolute NO GO for me.

Everyone has their personal no-gos. I immediately recognize repetitions in screen-printed tiles, which bothers me especially with wood-look tiles. Others don't notice this even upon closer inspection. Tip for the "closer lookers": Just don't mention it when visiting. You gain nothing and might possibly make the owner unhappy, as they will then see it too. It gets very expensive if you want to be perfectionistic in all details. Roller shutters would not be among my top priorities. The OP is also concerned about the costs, otherwise the question would have been unnecessary.

It would be an absolute NO GO for me.

I also think that there are far worse things. And you would hardly see it anyway, since roller shutters are usually only lowered in the dark by principle - and you are inside the house then, not outside. ;) Otherwise, I would first find out how much extra it would cost for aluminum all around.

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Unfortunately, our window builder has now informed us that a plastic roller shutter is not possible for the fixed-glass element due to its size. An aluminum element is necessary.
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It is the same for us.

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Do you think it stands out a lot?
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For us, (not yet) ... :)

What orientation does the bay window have? Would it be an option for you to equip only the bay window with a Venetian blind? You could keep the rest in plastic. Of course, you can see that, but it would be more of a clear distinction and therefore perhaps acceptable. I ask for practical reasons and from the experience of a bay window owner with a Venetian blind. The bay window (actually) lives from being used. In winter, it's very pleasant when the sun shines in there, but depending on the weather, from April onwards no longer. It just gets extremely warm behind it (and in the rest of the house). It’s somehow a shame to have such a large window and then possibly have the shutters completely closed for most of the day. For us, the Venetian blind is often down and tilted. Great light, still bearable with sun, and remains cozy.

What orientation does the seat window have? ...

Edit was already expired: I read it too hastily, it's about the other fixed-glass element. I agree with the majority of the previous speakers there. If you have to look at the costs, I would accept it. Only with the seat window, it is very impractical.