Here's why they might have made this decision:
* Popularity: The English dub of Bleach had been losing viewership and popularity. While it was a success initially, it may have lost steam due to changing tastes, competition from other anime, or perhaps a shift in the English dubbing market.
* Budget: Dubbing an entire anime series is expensive, requiring voice actors, sound engineers, and translation. Continuing the dub may not have been financially viable for the production company.
* Focus: Studio Pierrot may have decided to focus their resources on other projects, or perhaps the original Japanese version of Bleach was garnering more attention at the time.
The result is that the English dub of Bleach ends abruptly at episode 254, leaving a gap in the story that fans who prefer the dubbed version have to fill in by watching the subtitled Japanese version.
Some fans speculate that the dub may eventually be completed, but there's no official confirmation of this from Studio Pierrot.