i guess it's a lot easier to maintain, given the weather conditions in taiwan?
all bright and light coloured buildings become ugly in less than 5 years due to the rain and pollutions. and frankly, not many people care about it? look at all the TRA/MRT stations...
even in australia, where it's dry, not much rain and the air is clean, they still wash the building exterior quite often.
For commercial buildings, if operator own entire building is very easy to maintain. But if it is multi people own the same building then we will have issues, for example how do residents share the price, property right (you get someone don't want people to touch it), is it affortable...etc. The fact is most poeple in Australia live in a house rather than apartment. Most people in Taiwan live in apartment and form urban landscape we see now. Combine these two together will create issue happen in many Asia cities, for example Hong Kong city landscape.
It is easier said on the internet than exactly do it in real world. Unless we have enforced law or cleaning will all rely on people incentive. And what happen is, it is only happen when they have extra money in most of times.
However for this hotel, it is more likely it is not possible reason for them to choose this dark colour. It does not make sense as owner is hotel operator that they do maintenance and cleaness consistently. And you have boutique hotel! I doubt it is client aesthetic rather than weather.