My answer to this would first have to be a question right back at you: Why would they ?
Really, where is the incentive ? Anime became world renown without doing any of that, so why would they start now ? I would argue that it's that style, bred by their foreign sensibilities and culture that made it so popular in the rest of world to begin with.
Now, the second thing is, you are wrong. No they probably don't script dialogues in english, but that's a bit of a huge hurdle to put in their lap when they are already strapped for time on most projects.
However, they definitely know of the western/other audiences and take them input things( it can be general themes, or jokes that clearly wouldn't be in there if it wasn't for such audiences ) related to that. The point being that they are aware and influenced - in small or big ways depending on the project - by that part of their audience. The proof of that is that you have a few projects that get slammed by Japanese fanbases for seemingly altering parts of their work to cater to western sensibilities. That is something more often seen in the video games industry, because western influence is a lot more direct and palpable( to the people making money from it ) in that industry.
The third thing is, to follow up, that they still make most of their money, at least initially, from the home market. Simulcast and other such appearances of anime in a more direct manner in the west are bound to make these influences more numerous, whereas it used to be that the only thing western audiences brought was goodies/dvd sale's income.
The fourth and last thing is, in most cases, this isn't something that depends on the animation studios at all. To this day, most anime that are actually made come from manga( a rapidly growing number from light novels, and even mobile games, and some, completely original ), a market that is even more centralized to Japan. And the popularity( and therefore the likeliness for it to be made into an anime ) of a manga is almost solely based on the reviews/scores people give to the magazine publishers, chapter by chapter.
It's not to say that western influence isn't there though. A clear example would be Watamote, I encourage you to look into the popularization of this specific manga/anime. How different the reception was in america and Japan.