Part of the issue is irreversible transaction.
It would be safer to build a decentralized platform on top of Bitcoin where Bitcoin transactions can be reversed if unauthorized people gain access to users coins
You don't know what you're talking about. This would mean that anybody could reverse his transactions for no good reason. The merchants would have no reason at all to use Bitcoin, actually, it would be the opposite: they would avoid it.
Well any credit card transactions can be easily reversed by the credit card company or bank, but most merchants still accept credit cards.