Sorry for raining on the fanaticism being promoted here, but you don't need to have work experience. Saying that MBA is useless if you do not have workex is not true. It is however recommended that you do have some work ex so that you are able to relate to concepts with your own real life examples.
Instead, the most important thing that you should consider is what tifosi has posted in second post. That matters more than work ex.
The reality, in fact, is that a lot of people go for work ex first so that they get preference during the joining process, placement process and are able to command better packages.
Probably you are talking about management concepts but CAT is not supposed to test anything about that. Similar tests are used in organisations to gauge the development needs of the employees and judge whether they have the potential to move up in the organisation and take up more demanding roles. So apparently it does test something about management.
If you are talking about B-schools which are focussed on senior management positions then yes. I believe IIMs count among the best bschools but they don't need any work ex. Not everyone is trying get into Harvards of the world and doesn't need to either.
So if your question is whether there is scope, there is ample scope. Is it a good option, it is but it is also recommended that you work for at least 24 months first. Which stream should you go for, well this is the question that you need to introspect about.
I'd like to put some points in the open here -
Firstly, A is not a better manager than B simply because he has experience. But A will be better suited to tackle sticky situations, both personal and professional, as compared to B who will probably learn the hard way (which might include getting fired too). A first day recruit in the Army is not made a General to lead his troops into battle. A sailor passed out of the Naval Academy is not made a Captain on the first day for the same reason.
That said, everyone's potential is different and it might be that a fresher might do a better job than an experienced manager. But that is an exception to the rule.
Secondly, I can also say confidently, after doing months of research , that the top 100-150 MBA schools in the world do NOT accept you without experience unless you have done something extraordinary in college. In 99.99% of the cases, you need 3 years of work experience. Coming to the few Indian colleges which are at par with the best in the world, only IIMs accept freshers. Even ISB requires you to have work experience.
Again, I am no one to question the capability of an IIT+IIM graduate who is probably a very ambitious, dedicated, focused and intelligent person. But experience is still a quality that one is not born with. And it cannot be replaced.
Thirdly, I would like to add something about the 2nd-3rd Tier MBA colleges in India (for e.g. Goa Institute of Management). From what I have discovered, companies there prefer freshers. And there is a very simple reason behind that. Most of the students do an MBA to switch their domain. For e.g to get out of IT into Marketing, Finance etc. With 3-4 years of experience, a person is already earning close to 5-8 lakh per annum salary, if not more. Most of the companies coming to 2nd-3rd Tier MBA colleges offer packages of 5-10 lakhs per annum. So, for a person who was earning 5-8 lakh per annum, it does not make sense to opt for a job which is paying just slightly more. And neither does it make sense for the company. Most of the resumes of people who have 3+ years of experience are not shortlisted. That's the harsh reality which everyone should keep in mind.
I also do not agree that CAT, GMAT, GRE do not test your management skills. Rather they test how you might perform once you are
out of a business school and in a real corporate environment. Think about it. The key things tested are - how you balance your time, how to be decisive and quickly make a calculated guess for a difficult and tricky situation and move on so as to not waste time and how to eliminate wrong choices before even starting to work on a problem. Finally you do all this in a sterile environment under time constraints.
You can immediately do MBA if you want, but I would definitely prefer that a person should get some experience. I feel that even 2 years are more significant than 0.