Since this topic was ignored by devs (or not, according to Fleshwarped Casque buff), it seems that base War Cry is going to stay non-useful without specific items. Well, at least look at one of them - Krieg’s Mask.
Its -1 sec modifier is just not enough to warrant picking it over mentioned Fleshwarped Casque, even 5p Krieg set offers nothing amazing (just some flat Aether Damage, flat RR to Reckless Power - which is easy to get from other sources and thematical, but lame Krieg’s Wrath 
). I have two ideas:
- Change current modifier for War Cry to -3 sec for Krieg’s Mask to put it in line with alternatives;
- Or add -2 sec modifier for War Cry to 5p set bonus so that taking full Krieg would be an option.
As a bonus - please consider increasing flat RR duration on Krieg’s Wrath to 5 sec to match its cooldown. As of right now it looks redundant.