Not only because of the writer's strike, but also because the producers realized that the mostra wasn't moving at a good enough pace. They Lost quite a few viewers during Season 3 when it encountered quite a few episodes that were slow paced, and revealed little. Sometime during the airing of Season 3, the producers and writers set an end data for Lost, an unheard of action in the Televisione industry. The end data is set for the end of Season 6, 2009-2010, and which is also the successivo season coming up. This end data was set because the crew noticed that they were losing viewers, and it would be difficult to keep this complex mostra going without a an end in sight. Now that they have an end data and the rest of the mostra mapped out, the mostra has been dato shorter seasons, starting in December/January and ending sometime in May of each year, starting with Season 4. It originally had seasons starting in September of each year. The original plan was to air 16 episodes each season, but due to the writer's strike, 14 were aired in Season 4, and 17 will air in Seasons 5 and 6, making for a total of 48 episodes. This plan has kept the mostra moving at a brilliant pace that can be followed da fans, and also keeps the story interesting and engaging. As producer Lindelof stated, they are no longer stalling. They have an end in sight, and that is why there is a longer break between their seasons.
it was a longer break because of the writers strike. Same reason why season 4 was so short. And why seasons 5 and 6 wont have 20 some odd episodes like the first 3 season did. Seasons 5 and 6 only have 17 each I beleive.