Samsung Galaxy S 4 will have a 5-inch screen - why?

Samsung

The rumor says that the Samsung Galaxy S 4 (IV) will have a 5-inch screen. I don't get it, why are samsung releasing so many phones with different screen sizes? Are they still testing what the consumer wants? Are they unsure of the market? Or do they not know what they are doing?

Some voices heard:
Why are there so many models of cars?

Seriously, people want different things out of their mobile devices.
Quite stupid to do when the GS3 was launched in May.. Do they try to beat some record on having the most phones released in a year or what?
Android has a million phones trying to compete with one phone the iPhone. Need I say more?
It just amazes me how far one company will go to take down another. I know its how business is done. However, these guys are brutal! lol
Different people, different needs
The next Galaxy S and the new Nexus (whenever it gets announced) were competing to be my next phone. If it truly will be a 5" screen, I guess it's down to the Nexus to not disappoint me.
Samsung is just throwing darts in the dark, hoping that one model will stick. What is the phrase? Quantity over quality. What is the most popular Samsung model? It isn't even the S3 or S2, rather a cheap pre-paid version of Android. It seems that is Samsung's niche in volume is selling on the lower end.

One thing I hate about Samsung is their support sucks. Try to get help on a problem product of theirs. Regardless what product they produce I for one will never support their solutions when they can't support their customers. http://gizmodo.com/5933516/the-most-popular-samsung-phone-is-something-called-the-samsung-galaxy-prevail
Samsung is all for quantity instead of quality. Apple is the opposite.
That's because in a sea of similar devices, the cheapest one wins. If I'm a guy that is just jumping into the smartphone market and I don't have $200 to plunk down, I'm going to get the best thing I can get for the cheapest dough. That's why Apple making the two generation old phone free on contract is a brilliant move. Gets users into the iOS ecosystem without costing the user a penny without sacrificing Apple's quality standards.
Those pre-paid phones are actually not subsidized and they cost more. No what the pre-paid market is paying for is the monthly service which is cheaper. Look at Virgin Mobile in the USA as an example, their best rated phone is the iPhone 4S. It isn't cheap at all but the monthly and contract free is what they are paying for.