Phrasal verbs are very common in spoken and written English so we need them to understand and speak natural English.
There is also an interesting section on Particles used to make phrasal verbs:
All particles have a literal meaning: up and down , in and out , on and off , through , away and so on.
They also have metaphorical meanings. For example, when we say Please put out your cigarette, the particle out is not used with the literal meaning of outside but with the metaphorical meaning of ending.
These metaphorical meanings follow a logical pattern shared by many verbs and when new combinations appear they also follow it.
It’s very important to become familiar with the metaphorical meanings of particles. This will make phrasal verbs logical and much easier to learn and remember.