Checking some youtube videos, the blood is still white in the Japanese version of MGR, Sam aside, thus making that Codec dialogue something added (or changed, if it's replacing a codec in the original Japanese script) as justification to make the game more gory. Not entirely sure who might be to blame there, be it Konami, Platinum, or 8-4 themselves.
Considering that Metal Gear isn't exactly niche and generally takes place with western characters and locations, I suspect Konami was all too happy to
I expect for most companies, it's an issue of weighing what the majority of the western playerbase would prefer to be hearing as spoken audio, and/or a licensing issue, where including more than one language is either a costly affair, or the agreement between the seiyuus and the developer or Japanese publisher locks their voices to only that version (which I think has happened with XSEED in regards to Falcom's games).
Plus, in the older generations, for games that might already take up a large amount of disc space in their own original format, you could run into spacing issues in trying to include multiple full dialogue tracks on top of that existing data, and any other languages the game's script might need to have been translated into itself. This had a few solutions: Either include a single audio language (what most games do), cut the audio up to fit some, but not all, of the audio for both (Fucking NISA with AT2), or divide up the game into multiple discs (an actually smart move of NISA for Sakura Wars 5; Disc 1 is English Audio, while Disc 2 is the original Japanese, disc 2 being a whopping 7.5 GB in size) which of course adds further to the production cost. There's some cases of companies dropping the audio altogether for whatever reason, not even dubbing over it (such as Agetec removing the lyrics to "Windward Birds", as well as the combat-only voicing in Wild Arms ACF) too. At the very least, I suppose with blu-ray and digital downloads, disc spacing issues involving dual audio are a bit less of an issue, though now there's just plain old filesize bloat all around (just looking at the minimum required hard drive space for the PS3 Tales games in disc format, Vesperia PS3 needed 899KB, Graces f 4.3GB, Xillia 2.3GB, Xillia 2 3GB, and Zestiria a whopping 10GB, some of those having forced disc installations because playing them as is from the disc itself just isn't enough anymore).