So you are saying that they should not have scrubbed the last two potential launch times just because they would be flying into storms with the threat of lightning?
They don't only have to worry about taking off, they have to worry about an immediate emergency landing on the KSC landing strip if that were to ever to be necessary. (it hasn't yet, but it could)
If they can't see the landing strip due to the storm they took off in they are out of luck.
It's not like yesterday or today were their last options. I could see if they were down to their last window of opportunity and then maybe taking a great risk, but until they have no options left why rush it?