I honestly cannot tell when they do this. The music still sounds great. In some cases, it sounds better in my opinion.
They changed their style to appeal to a larger audience. The black album was the beginning of the transition and they completed it by cutting their hair. They left their roots in the dust and went for popularity. Its 'corporate' because they're being strung along by the record labels and producers rather than just writing music from their hearts.
So yeah, 27 seconds to the hook. Gotta have that mass appeal if you know what I mean. In case you don't: music has to appeal to a big audience to be "pop" and that's what Metallica fell into.
Compare that to the awesome song "For Whom the Bell Tolls", where the "hook" comes at about 2:40:
I'm actually somewhat of a musician. That is, I have a piano in my house and can read music and I play music every day. I'm not in a band or anything, because I pretty much just play for myself, but I know and understand music. In fact, I'll rock your fucking socks off on that exact song on the piano if you want me to upload a video to youtube - let me know. Seriously, I will upload a video of me paying that song on the piano just for you.
So seriously, there's the difference of "mass appeal" vs. music from the heart, so tell me if you're not gettting that point (no offense).
It is pretty emotional to me and speaks to me emotionally. What does it matter if they are not making music from "their" hearts but, instead are speaking to "our" hearts collectively?
The difference is the "corporation" speaking to you with what they want you to hear versus the band just speaking from their heart with with whatever you may or may not want to hear. The one side is being a salesman while the other side is being an artist.