Why we need the DFF to build the Register

Posted by geraldli on Mar 26, 2020; 5:55am
URL: http://nand2tetris-questions-and-answers-forum.52.s1.nabble.com/Why-we-need-the-DFF-to-build-the-Register-tp4034340.html

In this chapter. It says we can use DFF to construct a 1-bit register.

The final circuit has input(in, load) and output(out).  It’s easy to be implemented

My question is, why do we need DFF to construct the 1-bit register?
As far As I know, the dff works depending on clock pulse.

However, it’s possible to construct a 1-bit register without the clock input(I actually simulate this and it works. But I don’t know how to upload an screenshot here). It works under the same rules:
if load==1 then out=in
if load==0 then out is unchanged

It seems the clock pulse is unnecessary if all we want is a simple register.  The DFF with clock is much more complex.

Can any one help to explain the reason of using clock-based circuit  here?