This is kind of stupid.  Like in normal bitcoin transactions, payments are irreversible.  If there's no escrow, there's no way to "get a refund".  Once you've paid, you've paid.  What you are complaining about, is essentially that A has no possibility to steal back his money, and if he tries so, he risks to get screwed.  Well, the whole idea is that if you try to steal, you get screwed, yes.  With a normal bitcoin transaction, there's not even the smallest possibility to steal back your previous payment (unless you attack the block chain, and orphan the prong in which your payment was done - usually a more expensive undertaking than just propose someone to pay him if he kills B, say).  Now, the LN system may let you a tiny hope to steal your payment back, but it was designed to make this very risky.  You cannot use the tiny risky potential to steal in an LN as a normal way to "get a refund".