Fans want Lara back because:

- Lara Pulver is an absolutely equisite actress with so much talent (that voice).

- Irene is an interesting and complex character and her dynamic with Sherlock hasn't been explored to its full extent. We want to see how he'll functon when love of that form is in the mix.

- It would be very interesting to see the relationship between Sherlock and Irene now that John has his own family.

- The onscreen dynamic between Irene and Sherlock is reason in itself. 

- Having Irene return in Sherlock's mind palace and distracting him with a loving caress owes explanation/exploration of what really happened between them. 

- 3 seconds of naked Lara Pulver caressing Benedict's face in season 3 was not sufficient screen time for such a talented and incredibly beautiful actress (we need more). 

- A Scandal in Belgravia was by far the best episode, hence bringing her back would be apt.

- Irene is the 'Queen' of his mind palace and they need to have dinner.

- Lara Pulver needs more air time in general and putting her on the best British telivision show is certianly needed. 

- The rose in HLV was from the Woman, you cannot keep giving us glimpses of the woman without bringing her back!