For clarity, lets first establish the difference between the two:
Medical Insurance, otherwise also known as a Health Insurance merely reimburse the medical treatment bills. You will not get any cashflow from this insurance. I candidly regard this as an insurance to ensure your doctors are well paid.
Major Illness Insurance, on the other hands pays out a lump sum to You in the event of a major illness. It is cash at your disposal.
Lets ponder over the following to appreciate the benefit of major illness insurance :
How many, after a major medical ordeal, can go to the same work regime?
If not, will it be realistic for you to expect your employer to offer you the same wage for a lesser work scope or perhaps, even let you keep your job?
Without the income, will your utility company, mortgage bank and your children's school cut you some slack, and waive off the bills?
The answer is often a resounding "No". The bills will come like clockwork and your family may have compromise their lifestyle to reduce expenses. Not forgetting , the financial stress will often be in conflict with the doctor's usual recommendations - ample rest and avoid stress for better recovery.
This is why the payouts from major insurance from major illness insurance comes in handy. If well planned, the payout should be at least 3 to 5 times of your last drawn annual income; giving you the peace of mind for time to recuperate and space to think about the steps ahead.