Installing Arduino IDE on Linux I downloaded arduino-1.8.4-linux32.tar.xz and ran install.sh as outlined (the very sketchy instructions) in https://www.arduino.cc/en/Guide/Linux

This seemed to work OK, so I removed 354M of what I thought was the installer, only to discover that I had deleted arduino.

The so-called install.sh on closer inspection seemed only to create links into the uncompressed download in my home directory.

The whole process seems very un-Linux like; I had assumed that it would be installed in /usr/share/ like most Linux programs.

I realise I could extract into /usr/share/ and set permissions for other users, but surely there must be others who have wanted to do the same. The macOS version seems to have a proper installer; does one exist for Linux?
The problem here is that there are multiple flavours of linux each with their own installation and package management systems - Aptitude, Yum, EMerge, etc. 

It is not easy for Arduino to keep up with creating packages for each and every system, so instead they create a single tarball that can be used on any of the systems. 

At one point Arduino (or someone, anyway) used to create Debian packages for the IDE and upload them to the main Debian repository - however this has not been done for many years now and the packages in the Debian repositories are very much out of date (1.0.5 IIRC).

If you, as a system manager, choose to deploy the IDE system wide then it is your task to decide how best to do that.

One option is to just copy the contents of the archive to /usr/share/arduino and then run ./install.sh from within that directory.