There are many reasons for this, but basically I see that it is not yet universally accepted because there must still be objections. Just like you see a benefit, but other people don't see it as a benefit, try a product like cannabis, and you'll see ' why?'.
Cryptocurrency still not fully accepted and recognized by every government and the most reason I see for this is because of incapability of taxation. Since crypto is fully decentralized system it is hard for the government to control and collect taxes on every transaction but despite of this failure they can never take down the crypto currency because of its unique blockchain technology system and as as long as there is internet then crypto may continue forever.