How to translate 目的性？ This text is talking about the contrast between students in the past and now. In the past students blindly sat for exams whether or not they were relevant to their future job. Now, they are more choosy about what exams they take.

因此现在考证的人 更加注重考证的实用性，有更准确的目的性。

I think I can break this sentence into 2 sentences:

1。 因此现在考证的人更加注重考证的实用性。 

实用性： usefulness

2。 因此现在考证的人有更准确的目的性。 

目的： goal, purpose, aim,
目的性： goal ？？

Therefore today's examinees have a more precise 'sense of purpose （目的性）'?

Or did the writer just write 目的性 because he wrote 实用性？ Or is there some other meaning in '目的性’？ Could we just forget the 性 and write 有更准确的目的？
性, in this context, means 有...性质， having the characteristic/sense of ...   

So, 目的性：有 目的 性质， 实用性： 有 实用 性质.

You could translate 性 according to your contexts, and sometimes you could even ignore it when you feel it's unnecessary. It's all at your own discretion.  

In this context, I suggest using noun words, like 实用性: practicality, 目的性: purposiveness. And purposiveness is the same as "sense of purpose".  

有更准确的目的性。could be "be more clear/precise on the sense of purpose/purposiveness".