This question shows our mentality which makes us slaves of capitalists. Did you ever see an animal die of hunger? Even animals can get enough food to survive, why do humans have to work so hard to survive? In reality, they don't.
Human life is meant for higher thought because we have been given a well developed brain. If engineers were using their brains to develop some useful things for the society, I would have conceded that we should all be engineers, but let us objectively look at the kind of things engineers are working on:
- Facebook: What is the point of this? It is considered to be the best job for computer engineers in India. They go to work for a "dating" website. That is the epitome of success in India.
- Self driving cars: How much lazy will people be? Now, they can't even drive their own cars. What problem are we solving here? Who is benefiting from this?
- Amazon, Flipkart: Again, encouraging laziness.
- Processed food: A lot of engineers work in the food industry, where they find ways so that the food does not get "spoiled". What problem does it solve, realistically? Only thing that it does is encourage unhealthy habits and obesity.
- Guns, bombs: Who does it help, except destroy countless lives?
If you look at practically any of the inventions of engineers, you will find that most of them just encourage laziness and destruction.
Now coming to your question, why do we need education in arts and commerce? We need it to understand the real problems of life. The problems that philosophy helps solve, such as, suicides, violence, purpose of life. If we had good philosophers, they would help the society understand that most of what we are doing is pointless. Who is there to tell us about life? Who is there to show us that there is more to life than making money? History could teach us what mistakes not to repeat and what to emulate from the past. We can learn from Indian history, where the concept of "divorce" did not exist, how they were able to sustain such strong culture. From political science, people can learn the ways of politics.
One of the most ridiculous concepts that I learned in economics was Gross Domestic Product (GDP). It tells about the economy of a country by how much money they spend. You read it right, the economy of a country is defined by how much money they spend. It does not take into account the loans that the country took or how much resources and reserves the country used up. So, according to this definition if you have a million dollar house and a million dollar bank balance and you spend 3 million dollars in a year after selling your house and taking a million dollar loan, you are richer than a person who has a five million dollar house but only spent a million dollars in a year. Why is this concept not being challenged on a large scale? We need good commerce/economics students to do that. We need accountants and bankers to run the society. Where will they come from?
The problem is not with the subjects, but because our society is not giving enough importance to these subjects. So, we don't have many good teachers or good students in these subjects. These subjects need to be taught well because they are much more important for the society than engineering can ever be.