Although alot of people use it for the bad reasons, but the percentage of people using it the right purpose is more,and yes we do need bitcoin, since it has become part of our daily life, I really can't imagine the world without bitcoin now 
,bitcoin has made life so easy for most of us, especially for people in the third tier countries where doing any transaction outside the country is pretty hard, it takes some days or maybe a week for one to be able to send money to anyone outside their country, but with bitcoin transactions have been made easy without the middle man (the bank).
Yes it may be advantage on p2p from one country to another. This is one of the benefit having the bitcoin. Aside from that as mention about the transaction cost from service fee of the banks and remittances would relatively higher than to using bitcoin. However, there are also problems when it comes to acquiring bitcoin and that is by doing KYC. Most of exchanges are doing KYC on all of their users. And sometimes collect higher fees when converting fiat to bitcoin due to tax implemented by the government from their set rules and regulations for the safety of the users in that exchanges.,bitcoin has made life so easy for most of us, especially for people in the third tier countries where doing any transaction outside the country is pretty hard, it takes some days or maybe a week for one to be able to send money to anyone outside their country, but with bitcoin transactions have been made easy without the middle man (the bank).