Why would they make new Digimon Video Game for PS3 called Digimon Rumble and put it in English. but before that they made Digimon World Red Digitize for PSp and Digimon World Re Digitize Decode for Nintendo 3ds. And they never put thoses 2 in English.

This happens all the time with video games

They didn't think they would sell well out of Japan, they probably came to that conclusion based on a number of reasons. The sales and popularity of the game in Japan, the sales of past English released Digimon games, the sales of the 3DS in the U.S(portable gaming (3DS) is еще Популярное in Япония than consoles (PS3) where as in the U.S it еще of the opposite), etc.

If they don't think they'll make money, they're not going to bother trying to get together and pay a new team to translate and dub the game, new packaging, and a whole bunch of other legal stuff to get it released over seas.

It's possible that they might go back and release those games in English, but don't get your hopes up.