Putting the house number before the street actually is more consistent. Not using house numbers, but the number of meters from a crossing gives one a better idea of where the house actually will be. Some places issue house numbers in chronological order rather than in a geographical fashion. Some don't use house numbers at all, but give buildings names. In Japan streets usually don't have names, but the blocks (banchi) do. In India (at least in Hyderabad) there are street names and numbers, but if you want to go somewhere you need to specify the closest landmark - a temple, a shopping mall or maybe an office building.
Bangkok is no exception to these exceptions. Landmarks are also popular, but more to give a general idea where things are. Streets in Bangkok follow more the pattern of rivers than the grid pattern of North American cities with the smallest streets meandering until they flow into a bigger street which in turn meanders until it merges into an even bigger street.
Addresses start with the biggest street which has a name and then count down the number of side streets with odd and even ones on opposite sides of the streets. If the side street has its own side streets, this process is repeated.
It has its own logic to it, but it is confusing to new comers. You ask your hotel what the address is and they say something like "Soi 3." If you then walk around town for a full day and tell your taxi driver "take me home to Soi 3", they'll look at you confused. The third side street of what?