I'm not making it personal. But the way you're describing it it's like you're talking about a different show. Some of what you said is accurate. They did venture down too many peripheral storylines, but most shows do that when they last as long as Lost did. The way they resolved or didn't resolve some of them were clumsy. But again, you keep mentioning how ill-prepared they were. Again, I'll repeat, after the pilot they wrote a Lost "Bible" that laid out the mythology ahead. Then filled it in with details each season thereafter. Midway through the third season ABC gave them three more to end the show. So some of those storylines you thought got away from them HAD to either be abandoned or resolved quickly so they could move forward with the main story.
Another thing, sh*tty scripts? Barring a handful, I repeat, a handful of episodes each episode stood on its own as far as quality. The fact that each episode centered on a particular character enhanced the purposefulness of each episode - something few other shows accomplished.
The only people who were lost watching the show were those that didn't give it the proper attention it deserved. Lost, unlike most shows, asked something from their viewers - to pay attention, to think and to consider - and over ten million people from start to finish did just that. Give both the show and its fans credit.
Lastly, the fact that people still talk about the show's mythology years after its last airing shows just how great the show was.