I do feel Abe is falling back on China and NK as reasons to pass this as well and there is of course low probability we will ever see any real conflict in East Asia.
But I wouldn't necessarily say Japan has is totally isolating themselves unless we are not counting the US.
The problem is that the US has been in Japan's corner since the 1950's and these bills would do nothing to strengthen that support. And that on any foreign affairs issue other than defense, closer ties with the other East Asian countries are probably more useful than American support.
Japan needs to find a way to make nice with China without completely capitulating. They have so much to gain from a closer relationship with China, antagonizing them is dumb. But they can't roll over and let them have their way either. Honestly, they're in one of the toughest situations of any country in the world when it comes to international politics. There are no easy solutions for them.
Japan is so geographically isolated and territorially secure that international politics should have been quite easy for them. And in fact, they used to have pretty good relations with just about all of their neighbors other than North Korea. Even the territorial disputes with China/Taiwan and South Korea were stable and without much acrimony. This should all be attainable again, but not with Abe as prime minister.
I think their best bet is to cooperate with China as much as they reasonably can and pull back somewhat on their alliance with the United States. That said they shouldn't pull back too much because we're the only thing preventing China from attempting to throw around their weight militarily down the road. It's an extremely delicate line to walk, but it's in their best interests.
There's no need to pull back for the US. The US asks almost nothing from Japan other than a few diplomatic gestures, so as long as they maintain those, all will be fine. The question of China is a lot trickier, and I think that Japan has to ask themselves what China's future role is in East Asia, and whether they can (or should) do anything about it. There are going to be a bunch of unpleasant truths in that examination.
If people cared more about politics this never would have happened to begin with because Abe never would have gotten re-elected.
But it's just not something a majority of people care about until it's too late to change things.
Why do you assume that the Japanese public has any pull on Japanese politics?
Their constitution could also be seen as a symbol of shame. A constant reminder that they lost in a previous war, and were imposed limitations no other country has to deal with.
I don't see the problem with turning the JSDF into an official army. They aren't going to suddenly turn expansionist, and there are cases where armed intervention on foreign soil is the decent thing to do.
Besides, wanting Japan to be unable to act outside it's borders, while also wanting western nations and the UN to do something about ISIS, sound a bit hypocritical to me.
The problem is that it doesn't do anything to increase Japan's security and it weakens Japan's political position in East Asia.