I wouldn't say they were ripped out so much as they were never really implemented in the first place. HG/SS were developed more or less concurrently with B/W, and the games core mechanics evidently split off fairly early during developments, which is why HG/SS have (imo) a much nicer user interface with the menus and the box control system, among other things. It's pretty common for this to happen in studios, Black Ops has been in development for a very long time and another CoD game was being developed by IW in the mean time (still is)... but yeah, my point is that B/W don't have the walking Pokémon because they were never programmed in. It's a safe bet that they'll be reintroduced in generation VI given how much of a hit they were, or maybe even a sequel withIN gen V, but until then we'll just have to let it go, because what you're requesting isn't a hack, it's a really complicated cannibalisation of the game's code that no hobbyist is going to pull off.