Now a days bitcoin are widely accepted and it is decentralised currency.
Due to its decentralisation some countries do not accept as the payment system.
Is bitcoin needs some regulation to use widely and accepted by all countries ?
I don't understand what OP is trying to say,what do you mean by bitcoins need regulations?or it supposed to be bitcoin usages needs to be regulated?
Decentralization is the main reason that bitcoin was invented so we can't do anything with that.
No,it is already in the better form, bitcoin doesn't need to be regulated.Only the countries have to adapt to the new technology.