There's a TL;DR at the bottom. Wall of Text: The cool down isn't even that bad. They might scrap the whole idea before release, which I doubt. I'm all for innovation. Who knows how this will play out. This can relate to civilization and technological advances. With each MC update needs are fulfilled by Mojang for the Players. The printing press, for example, was created by Johaan Gutenberg. He didn't necessarily know that he would increase the rate at which information traveled for the time, being around the 14the century, correct me if I'm wrong, please. With the printing press, it made the Bible readily available for everyone to purchase because previously it was very rare and expensive, so only the wealthy had them. Scientists, and other related occupations, have a faint idea of the possible outcome from a technological revolution, but quite often it goes in ways we didn't expect. This can be applied to the updates, like 1.9. TL;DR: Each Minecraft update is similar to that of a technological revolution in real life as each update fulfills needs, but can bring new ideas or concepts that we never thought would be possible because of the revolution. It also creates new needs.
I actually like the cool down. It brings more of a tactical feel to pvp, instead of 2 guys running at each other with swords, You can have guys with axes that do more damage per hit, or bows that take time to aim. And even if you don't like it, you can mod the items on your own server so it nulls cooldown.
Yes. There really is no tactic in how pvp works now. It's either combo or done. No reaction is needed and no skill is needed.
1.9 pvp is basically hit, wait for the cooldown, opponent hits, waits for the cooldown, just trading hits and whoever wins has the better gear or hit first.
I would have to disagree. Pre-1.9 takes no concentration. I can literally win by spam clicking & following. In 1.9, you don't have to attack every time it refills. Infact, that's what'll get you killed, as your attacks can get predicted and mulled with the shield. Instead with 1.9 pvp, you want to attack randomly after it's filled. That way it'll be harder to null your attacks and get more damage on your opponent.