Disagree
For example playing against mech eldar with AC heavy DW and it's pretty much an auto-win for the Eldar before any dice have been thrown. AC's rending doesn't work on Wave Serpents, and they have the mobility to stay away from 24" while shooting you.
CML's allow you to shoot stuff at >24" that you absolutely don't want near you - MM Land Speeders, Transports with nasty stuff inside etc, or stuff that can shoot you from >24" away.
They also cost 10pts less than an AC and their Marine counterpart CML's, freeing up points for a ML Dread arm, couple of chainfists, combi-melta on a Chappy or Lib etc