I totally agree 
I like yad , it can do multiple things in a single window, it is indeed a major enhancement compared to zenity.
One step beyond yad is gtkdialog which can be used to build complete graphical interfaces.
It has become abandoned, picked up again, forked at least three times etc. so although it is a pretty good interface for bash scripts, and I really love it, its future is uncertain.
The only reason i reverted to zenity for this hack is the fact that it is already present on every Ubuntu-MATE install so nobody needs to install extra packages to get this running.
I had some thoughts about doing this in gtk/glade + C or wxglade + python but that is a bit much work for what I consider as a temporary stopgap. Also a bit harder to post in the forum. 
It would be much less work to revert to the old tried and tested slick-greeter.
So that is how i came to dig up the old zenity