Missing Drumset?

I've been using the Drumset instrument within MuseScore since around 3.5, and when using an old score to make a new piece, I found that you the Drumset can't be added and is not found in the list of instruments anymore. The midi is still in the files though, and certain pieces that I've worked on still have a functioning Drumset.

Upon further reading I also discovered that the 4.4 update will introduce more features for Percussionists.

Does that mean that the removal of the Drumset from the Instruments list is a start to removing possible redundant features or it is just a bug in the system?