As we all know now its a competitive world. Some colleges and universities ask 90% cut off to get admissions? Do you think its right ?

To some extent.

Definitely this is not fair.  But the reality is, such institutions are looking for ways to make money the easy way, which the rich parents of above average students (i.e,60% to70%) are willing to pay.   This situation was created by parents themselves, which has affected others who cannot afford.  So, in a way, even though you have to get90% to obtain an admission, it is not strictly followed in the above case.

I think the cut off marks is made high, since the ability of students in today's world are far more better than in the past and also this is done to weed out students who does not have the drive to get the above90% marks (by becoming bookworms through by hearting the lessons and not having practical sense), even though they are successful when they come out in practical life, in comparison to students who got90% marks. 

I have total respect for people who gets high marks.  But I think their value will increase only if they prove that they have the practical sense to manage situations effectively in the real world, which is very tough. 

As you mentioned, it is a highly competitive world.  Therefore, a person's status is calculated based on the money that he earns and not just by marks.  After all, the purpose of studying, is to be a good citizen for their own country and earning a good salaried job, to handle their family life comfortably. By being bookworms, the maturity and understanding of a person today is not as it used to be in he past.  

Our parents had difficulties in life and they used to face it when they were children.  So, their maturity and understanding practical situations were far more advanced at the age of20, which isn't seen today, due to spoon feeding.

Practical fields that require high marks definitely will earn their respect due to the marks and their calibre to handle practical situations according to the requirement. But it is not so for the general occupations.

Not always wrong.

 Let them have a try! It is good that not all colleges and universities have the same requirements. I wish some colleges and universities will try an admission system based on one or two subjects only and see the results. I personally think high of those who score high but at the sametime I appreciate those who are talented and get high scores in one or two subjects.

I see that there has to be the essential aspect of industrial and career based aptitude which will help students think more in terms of careers as well as professional expertise rather than merely qualifying for cutoff percentages in colleges and higher institutions.  It is often seen that a90% student is less practical in a professional workspace as compared to a70 percentile.  Reason - people learn but do not UNDERSTAND what they learn - therefore Theoretically a90%, but practically ???

In Russia, it is not so cruel.90 % can be cool but then who will enter?

I see that this issue schould be managed to meet expected demand in the job market. Fairness to sudents is more to teach them what suits them and they can use to get a job.