In the London riots of the 1980s, a lot of shopkeepers boarded over their windows, even though there'd been no riots in the immediate vicinity - that was a fairly logical response, they were already targets because they were, y'know, shops. Another instance that happens all the time, but doesn't get any publicity that I know of - Lewes, in East Sussex, has a huge November 5th celebration (you've probably heard of it to that extent) - a crowd of 30,000 in its tiny, medieval streets isn't at all uncommon, especially as its on Brighton's doorstep - 250,000 people - though the direct trains to Lewes don't run on 5th November precisely because of the overcrowding. And shopkeepers there nearly all board their windows.
So, when its a common thing and everyone does it, for good reasons, you won't stand out. If you're the only one doing it, like the others and you yourself imply, I think you're asking for trouble.
People do have decorative grills - do an image search for that phrase, and you'll find some nice ones - but depending on your house and area, you'll still stand out. A neighbour in a ground floor flat in East London got some after the riots, though they definitely looked like prison bars
I wish these things were common in the UK
https://www.samsondoors.co.uk/security- ... -for-homes
I've seen them on very ordinary houses all over Western Europe, but they're not a thing over here.
Not letting light escape is the basic, and thats a fair amount of work in itself. Then its about securing the frame of the window/ door - longer length screws. Keeping your windows locked (and the keys available so you can get out in case of fire). But the truth is, any nutter with a few bricks to throw can break your windows, eventually.
To you specifically, nightowl, bay windows - what's outside? Can people walk up to your windows? Is there a fence (asks she, fenceless ... )? You could put a wrought iron supports for windowboxes, maybe? You could even grow plants there that are pretty, and also have a prepperish use. Make it hard to get to the window: its like the cliche of running away from a bear, you just have to be faster than the slowest person in your group
HTH