Simply put it's because they lost their ways when Nataf joined.
Like a lot of other brands, key people didn't understand the concept of a brand in it's whole, and it's most important part : the image of the product. A brand has to stay true to it's roots, and the only way of expressing this is by design codes wich makes the brand unique. So that a customer can relate to the brand, and stay related to the brand in the future.
Another way to explain this: if you take a watch from a well established brand and hide their logo/brand name, you should always be able to tell which brand it is. The two best examples are Rolex and Richard Mille (please chill guys ! I'm talking design codes here, and only that).
If I remember correctly, Zenith lost their soul when they came with this horrible open dial with view on a poorly finished balance wheel and surroundings.
At this price point the Monza seems to be nice. (I first thought it was like 15k to 20k and wasn't OK with the level of finishing).
Please note the El Primero does have an important flaw (I don't know if they ever corrected it), and if you see grease full of black particles near the automatic ratched wheel , you need to ask for a service ASAP. Here's the problem, please take a seat before opening. obviously NSFW.