The short answer: because you have to prepare for them.

We all hate standardized tests. We feel like they don’t measure our true fit with the places to which we are applying; they aren’t a true measure of our intelligence; they yield a single static number and we are dynamic flesh-and-blood people!  

But you aren’t going to get anywhere if you draw a line in the sand against standardized tests.  Taking that moral high ground will exclude you from all the opportunities available on the other side of test day.  

What you have to do is prepare the best you can for those standardized tests.  Ace them. And then go on to the programs and schools of your choice and be successful.

Likewise with job interviews. It’s tempting to think:

I’m good with people.  

I want them to see the real me.  

I want to be genuine in the interview.  

Those are true! But you also have to be prepared. You can’t be taken off guard by commonly asked interview questions (see posts here and here); you can’t ramble on and on (see post here).

You have to practice so that you have clear, concise answers that are prepared well enough to deliver them naturally.  You can’t deliver them like a memorized script or like a robot, but you can’t show that you’re thinking about these things for the first time in the interview.  

That takes a lot of preparation! But like standardized tests, it will pay off when you wind up with the job you want and the career success that follows.