Is it important to be a co-author when PI takes first authorship on your work? I have been in biomedical research for a long time without any good number of publications.

Recently, my work is now being published by my PI. My PI asked someone else to do another part of work. I was then asked to email the methods and results but did not provide me any chance to write a paper. Now I am placed as a second author on this paper and 6 other persons out of 9 are guest authors. I can see that this paper has at least 60% contribution from my work. It is emotionally hurting and extremely disturbing to see this unfair authorship practice, which I am asked to silently accept. It is even more hurting to see the names of all guest authors who I only know by name but never contributed a dime of work to this paper.

Should I accept this issue silently? 
I'm aware that the universities favor their faculty members, no matter how many nice words are posted on their webpages on authorship misconduct.

Would it be wise to withdraw myself completely from this article?

Any other options?

I was advised by another faculty member that some very senior PIs still work in old-fashioned way of authorship, where they always want to take first as well as corresponding authorship, pushing postdocs on second spot. Besides, accepting this unfair practice would still not be so harmful for future employments as prospective employers can still figure out based on the names of authors that first person is a PI and the next one is actual person who did the most work.

Is it true?
I don't see any logical reason why you should withdraw your name from the authorship list. This only hurts you in the long run. You should want to have credit for your work.

You might politely ask your advisor why the "guest authors" have been included, and what contribution they have made (since you said 60 percent was your work, what about the other 40 percent), and then discuss it further if you don't like or aren't satisfied with your advisor's answer.