By taking levels of rogue, you are decreasing your versatility (due to feat loss) and your damage potential (due to loss of BAB). In additiona, to take advantage of magical enhancements, you are now required to have twice as much treasure tied up in your weapons to keep pace with two-handed fighters.
Sneak attacks are only useful at the beginning of combat or if you are able to position yourself appropriately. Positioning yourself appropriately often takes a move action, thus skipping out on extra attacks at higher levels, again limiting your damage potential. They don't offset the benefits of fighter feats, BAB, and higher damage. If they did, then rogues would be better fighters than fighters.