Use of mir with kaufen

Lesson 10.8 includes the following two examples:

Ich kaufe mir die/eine neue Hose.

Ich möchte gerne eine neue Couch kaufen.

Two questions:
It makes sense to me that "mir" would appear in the first sentence, but I don't understand why it doesn't appear in the second.

What does "gerne" add in the first sentence? The translation "I would like to buy a new Couch" makes it seem like gerne isn't necessary.

Hallo RobS49,

The mir in "Ich kaufe mir die/eine neue Hose." - "I buy the/a new pair of trousers."  is emphasising that you are buying the new pair of pants for yourself. If you left mir out of the sentence it would not be clear for whom you would be buying them - it would just be a very general statement. A more literal  translation would be "I buy a/the new pair of trousers for myself."

Julia,

Thank you. I appreciate your insight, as always. As far a mir goes, I understand it's purpose as you stated. What I don't get is why mir isn't used in the second sentence. I would assume the person is buying a couch for themselves in that scenario as well. I can accept the lack of consistency. From a usage standpoint, I want to make sure I know what is standard. Would it be incorrect to leave mir out of the sentence about buying pants? Would it be incorrect to include it when buying a sofa?

Thanks.

Hi RobS49,

it really comes down to personal preferences as well as if you want to highlight that you are buying something for yourself or not. 

All of the below are correct:
"Ich kaufe mir die/eine neue Hose."
"Ich kaufe die/eine neue Hose."
"Ich möchte mir gerne eine neue Couch kaufen."
"Ich möchte gerne eine neue Couch kaufen."

Grüße
Julia

Vielen dank, Julia. Du bist wunderbar. 

Gerne!

Grüße
Julia