Why should we have DC breaker/ DC switch in the power inverter?

Many inverter manufacturers won't add a DC breaker/DC switch in their inverters in order to keep it at a low cost. Anyway, without a breaker, it is not a big deal for power inverters as it is still functional. 

However, under safety considerations, it should come with a DC breaker.

Why?

1. No spark when you connect it with the battery bank.
2. Reduce the risk of spoiling it during installation. We know, improper instructions are the main factors to spoil inverters since there is no guarantee for every installed man with a professional technician background.

For example, when it should connect with positive "+" to positive "+", some people connect it with positive "+" to negative "-", the inverter is likely to be spoiled instantly. However, if it comes with a DC breaker, you have time to check and revise it properly.