1) It’s not LIVE. If you really want to know what went down on SmackDown, you can find out two days before it airs, because it’s always taped Tuesdays. Live is more exciting & no temptation to spoil the results by finding them online days before.
2) The storylines never make any progress. I know that as long as I watch RAW each week, I can stay up to date on the storylines. Despite the fact that WWE has SmackDown & Main Event, nothing actually changes with the storyline. I could go four years without watching a single SmackDown, and I’ll never miss a beat as long as I keep up with RAW.
WWE seems to be attempting to push SmackDown a little bit more. They had Daniel Bryan’s first match back since his injury, on SmackDown. They also gave the show a new night (or old night, since it was originally on Thursdays).
Regardless though, until the WWE changes both of those issues, Smackdown will always be seen as a second tier show.