Firstly, the act itself of region-locking the product is not that bad an idea.Oh yes it is! You bet your hairy little *ass* it's a bad idea!
(If you're wondering why, study the emphasis [I added] in the quote above.)
On a purely technical level, it enables modifications for local language and laws (e.g. UK Censorship) and licensed distribution for local distributors and copyright owners.And which of those couldn't be implemented, as you said in your headline, with Region Coding? Oh yes, quite a few, probably: Censorship, and presumably "licensed distribution" (if by that you mean the discriminatory and extortionary practices the MPAA and RIAA want to see made universal law).
But who gives a shit? Censorship isn't worthy of any defense at all -- certainly not enough to warrant building it into devices *for you(?) and me*, who live in more enlightened places than the UK, at least. And the "licensed distribution" seems to work damn well already, with other media, such as books and (old-fashioned, genuine, standards-compliant) audio CDs: You sell the media to me, and the "license" to the content is thereby "distributed" to me.
The only "technical" argument that stands up, of the ones you mention, is that "it enables modifications for local language". That'd be nice, so -- for instance -- my fiancée could watch a film with Swedish sub-titles, her son see it with Finnish ones, and I could see the same film without any at all; all on the same player. And for that to be possible (or convenient), we REALLY DON'T need any damn *locking*! On the contrary, that only *deprives* us of the potential benefits of "multi-regional" (for want of a better word) "media content".
For typical DVD content, it also permits staggered releases to follow theatrical or television releases.And what's so great about staggered releases in the first place? What interest do *I*, as a consumer -- and thus the legislatures that we, us consumers, (ostensibly) elect (allegedly) to represent us -- have in some fat-cat media mogul on another continent being able to stop me from (or at least making it useless for me to) buying a DVD on a business trip to America and taking it home with me, just because the (over-priced) cinemas at home haven't got around to screening the movie yet? Am I somehow morally obligated to subsidise Hollywood moguls and/or European cinema chains?
Moreover, Nintendo, Sega and Sony have been doing it for years with their games consoles.Yeah, and (for those who care -- I'm not a gamer, myself) THAT SUCKS, TOO! Is that somehow supposed to be a defense of the practice, just because some *other* group of extortionists is doing it (and, unfortunately, seems to be getting away with it), too?