Online merchants might have a problem accepting bitcoins because it sometimes takes time to get a confirmation - as long as 30 minutes. How do you sell your products on automation with that?
I don't really see a problem with waiting 30 minutes for an online transaction.
It's not like most places are going to ship your merchandise before 30 minutes anyways.
The wait would be a bigger problem for someone buying something in a store, since you would want to walk out with the goods before waiting 30-40 minutes for the transaction to be 100% confirmed.