I main a warlock if I completely miss with my ranged melee I lose the charge. it's the same with the hunter throwing knife. And the Titan melee is way stronger and is available in every subclass!
Because it is ranged. It leaves your body. Same with smoke bombs or throwing knives as well. Titan SC is used primarily for mobility, and secondarily as a knee-jerk reaction. Taking that away every time a Titan used his charge would kill off any SC Titan tree forever