It can indeed be frustrating, but this is how i see the situation:
A random WZ is the same as a random FP. It's a PuG (pick up group). Noone owes anything to anyone except performing their role while a part of the group. This means, even if it's considered impolite and rude, noone is bound to stay for the whole match/run. People can leave whenever they want.
Yes, by doing so they put their former team into disadvantage, but this is how the system works. The only things devs can do is either completely forbid leaving the FP's and WZ's before they are completed (which is ridiculous), or implement some sort of penalties.
As a player, you can overcome the said issues by playing in an organized group, let it be a pre-made or a guild run. This is why people organize into guilds, no matter PvP or PvE focused - to have reliable people at their side.
Well, you're definitely not waiting endlessly for a person to click his "ready" button. When a FP group is formed, there is a 1 minute window for everyone to accept their roles. If a person doesn't do it for any given reason in the said time frame, he's booted from the queue and the remaining people are placed on top of the list.
Ok then can we get the ability to put people on ignore and not have to queue warzones with them too so we don't have to deal with people like you more than once? While there is no actual punnishment to leave we do have the ability to ignore those we do not want to group with for GF so we do not have to deal with them more than once if they make our game less enjoyable. Why not allow the same for Warzones?