I think IT has it’s applications. Previously I have used an IT system on a materials handing plant where downtime was costly. On detection of one motor fault the system could continue to run until a second fault was detected (with the faulted motor being replaced when system demand was not high). It is more difficult to implement and we had to use earth fault monitoring and Petersen coils. While I would use it (and can see benefits) on a special installation like this one, I would generally prefer a TN or TT system on more common installations.