Definitely a niche application these days. There are certainly cases where it would be best, or at the very least, more beneficial or even more organized to use the old Prefix/Suffix for an advanced voice command system of some sort... but like Pfeil already said well enough, the dynamic command phrases and {CMDSEGMENT} tokens are perfectly suited for the majority of cases.
I still prefer to use Prefix/Suffix for in-game radio style commands when the Prefix section would be who is being addressed (i.e. Alpha Team, Bravo Team, All Teams, etc.), and when the sub-commands for each individual team may vary slightly depending on who is being addressed. This allows me to enter the 'main body' of actions contained in the suffix with a variable already set by the Prefix command of who is being addressed, for the logic in that 'main body' to utilize as appropriate. Examples of these are available in my public profiles AVCS4 Falcon BMS Radios and AVCS4 SWAT Radios (for the Ready or Not game).
For most everything else, and even within these Prefix/Suffix command phrases, I make extensive use of dynamic command phrase structures.