No surprise. Detective/investigation is one of the popular genres in the world....and there were dramas like Aibo and Kasoken no Onna that come up with new season every single year.
Law dramas are popular too but not as detective/investigation. But the most important thing is these 3 genres can be made "1 case per episode" which is a major selling point for those who like this kind of episodic format.
Business theme on the other hand is one of Japanese specialties I would say. While there are exceptions, I found many interesting Japanese business dramas as compared to other countries. They tend to focus more on technicality of the business instead of the side stories or main/side romance, which what I like about it.
I would not trust the tagging in MDL though. Sometimes business tag/genre does not mean the drama main focus is business. It could simply just the settings of the drama in the workplace. You need to further check the synopsis and reviews to know what it really is.
But it's not strange to find many Jdramas involving work/workplace as we know Japanese is a super workaholic society...so you get the idea. And you will get as many kind of weird jobs as possible in Jdramas. Not for the sake of giving the character some fancy job title like what other dramas did, but they will go in-depth with that job/work too.
As for the trend, I don't consider the above as trend because it was like that since long ago (I guess starting from the late 90's). Before Kdramas started to diversify their genres, Jdramas were the only one that available with many options like this.
