(Note that its a wide modification, so for those of you that may care technically its not colemark DH, but rather colemark DH-wide that I'm using, if you don't want the column in the middle you can just not use the wide version).
Nah, that's intentional because having your hands close together at the angle you use when typing normally is bad for the health of your wrists and can lead to RSI in your wrist over time if you are on the computer too much. If you have a proper ergonomic keyboard its unneeded, but it should help to some degree if you just have a normal one.
It also... doesn't really impact you in any real way that there is a gap in the middle since you just move your hands one letter farther apart but everything is otherwise in the same relative position (unless you need to type a bunch of brackets, it might matter there, but in that case note that the cap lock key also alternates the entire keyboard as a alt-function).
I'm not really fond of the = going in the middle there instead of the end though, might end up swapping it.
Why would one ever want to switch the layouts, though? What's the benefit?
Benefit #1: More ergonomic, you will have to worry about RSI and carpal tunnel less and if you already have it to some degree will feel less pain after typing for extended periods of time. I was kinda starting to get pain in my hands (because I'm doing a online schooling thing right now and typing a ton) and want to avoid it getting worse. Even if you don't have any your hands will get less tired over time typing.
Benefit #2: You should be able to type faster once you actually learn one. Eventually.
Benefit #3: Colemark at least (apparently, I'm not really there yet, but I very much kinda see it already) is apparently just more fun to type with then qwerty.
Now, it does come with a pretty hefty cost: Learning takes a ton of time to wire the new layout into your muscle memory and you will be initially miserable and unable to type and after that still far slower then you were.
Everything I've read on the subject agrees that qwerty is kinda not great, so on the time scale of a lifetype its probably worth it to swap over if you type enough.
E: Really though its still very early days for me and all I'm operating under is some hype from some sites, I'll see in a few months how it ended up going and if it was worth it (and it almost certainly will be if just for the ergonomic benefits even if the other benefits turn out not to exist at all).