Correction: they're not dangerous if you know how to use them.

Most people would expect to be able to safely pass the contents of $1- to any command without the contents being evaluated an extra time, because that's how most commands in mIRC work.

It only takes a very simple example to demonstrate the security risks associated with these commands when not used correctly.

Code:
//scid -r echo $!time


vs.

Code:
//echo $!time


If you pass anything that contains unknown parameters ($1- in an on text event for example) to /scid, /scon, /timer or /flash, then you're in for a world of trouble.

It's also very irresponsible to try and play down security risks unless you have a complete understanding yourself.