You are right on the "featurism"
In fact, GParted is mostly related to gnu parted and a number of other free/open source tools related to the partition resizing and moving operations.
More features need much more development and maintenance effort. The GParted team is quite small, so much of the effort concerns bug fixes, support for newer hardware and software, and development of functionalities directly related to the resizing work.
We don't have to forget that GParted is used on many filesystems, partition table types, on single hard drives or RAID arrays.
This doesn't mean that new features are rejected. Some of them are added as long as there is time and free/O.S. software tools for them. Of course, work for such features by volunteers is always appreciated.
Restoring the boot functionality on a mswindows system is usually done from the recovery mode of the install cd/dvd of this operating system.
Information on the master boot sector and extended boot record structure can be found in the following pages:
Keeping backup of the M.B.R. can be dove with the dd command.
Restoring the M.B.R. is tricky, because we need to know well which part of the M.B.R. we want to restore: boot code area, disk ID, partition table.
In older GParted Live versions, a special tool was included, developped and offered by a member of this forum. This tool was able to dump contents of the M.B.R. or partition boot records to files. Unfortunately it didn't work in more recent livecd versions.
*** It is highly recommended to backup any important files before doing resize/move operations. ***