Hmm... the OP is abit off...
the title asks about multi-languange, while the post refers to something else.
Okay, so Nethalite. People like Japanese voice with English subs because it feels better; it feels more original, and sometimes, things from different languange won't fit when you translate it to English, thanks to the way Japanese languange works, many puns created in Japanese won't work AT ALL when you translate it.
A simple example is 'ookami', literally means "wolf". Now, when you pronounce "oo" part in 'oo-kami', by modifying the length of "oo" you can make it a vague pronunciation between a simple "o" and a long "oo". 'Ookami' by itself means "wolf", but modify the length of "oo", and write it in a different but have the same pronunciation kanji, it can mean "Great God". this method is used to name the game "Okami". So while Japanese may consider "Okami no ookami" (I think it literally means The Great God's wolf, as in, his/her pet wolf) as a pun, in english it's plain "The God's pet wolf", nothing pun-like at all
Sometimes, pun isn't everything, there's something cool in "Kagebunshin-no-jutsu!" compared to "Doppleganger technique!" or worse "Shadow clone technique!". The feel of originality just cant make it up. The same can be said to "Senbonsakura", Byakuya's technique. While they translate "chire" to "scatter", they didn't translate "senbonsakura", because saying "cherry-blossom" takes too much time, and Byakuya's lips doesn't really move that much. On top of it, the word 'sakura', let alone 'senbon' makes it feels original and cool
The problem isn't about the sound-files file-size, it's easier than that: Why don't the developers put English sub-titles instead of having English voice actors?
f course, you can't say that to ALL games. Prof. Layton is much better in English
Also, sometimes Japanese voice actors did better than English voice actors. Take, for example Byakuya. Byakuya's Japanese voice is deep and full of dignity, something the English voice actor can't achieve.
That's why many people prefer it this way: Japanese voice and english subtitle. It's cool, yet you understand what they're saying. However, since you've got to look at the subs, you might miss some cool events that are happening, since your focus is on the lower screen, you can't really see what's going on on the upper screen, that's why some people try to endure and hear the English dubs anyway. At the cost of coolness, you can watch the video in full