Let me introduce you to Tirana, Albania which has done exactly as you suggest! They elected a former painter as mayor in 2000, and the rest is history. So many of the brutalist buildings in the city are now covered with bright colors, murals, patterns, and more. You can check out some before and after images here: https://blog.ted.com/9-views-of-tirana-albania-with-its-bright-multicolored-building/
That said, yes, their tendency towards large unbroken planes of material make them prime candidates for murals, and you see a lot of that in places like Chicago that had a big Brutalist phase.
I feel like most brutalist buildings are designed by a committee. They want the building to look like it provided maximal value for money, so they try to avoid looking good.
Not sure if you're making a clever joke, or if you don't know that brutalism is defined by using steel and concrete in large blocks. Might be a mega "woosh" on my part though haha
Some graffiti is, I think, traditional at this point and a good mural can do wonders to humanize it. I have a feeling that patterns are not actually going to improve it though. The problem is often the form rather than what the material looks like. You could paint it to look like a row of thatched cottages but that would to me be even more depressing.
You are also then committed to repainting it regularly or it's going to quickly look even worse than when you started.
Vines in my opinion are great dicore maybe that's because I'm a sucker for abandoned building vibes idk what it is that makes me love looking at abandoned buildings it's one of the reasons I love portal 2's abandoned sci Fi look if I wasn't for the high heights and turrets I would love to explore abandoned apeture
Graffiti is vandalism. It is not traditional, and it's not art. It's a crime; there is no exception unless it's done on private property with permission from the property owner.
It can't quite get brutalist buildings to look as good as non-brutalist buildings, but yeah painting them is a great move that really improves the vibe.
I feel like I remember reading about a city that basically encouraged graffiti, and would rotate through local artists every few months or so. Seems like a great way to give the place some character