I'll be honest, without Ran, this show will be the same (or more awesome) to me... She is so dependent on the character Shinichi, always appeared as Shinichi's ideal lovers, that if there is no Shinichi there would be no Ran. I'm sorry, but i feel like if there was no Ran, there's still a Shinchi fighting with the BO, he could still find a way to deal with them and other characters remain the same. Ran existed to make the show more romantic and attract more female fans, but for a detective manga, her role is too small, beside romantic moments with Shinichi, i don't find her any special. As a main love interest, Gosho has put Ran in the wrong position, being always a naive one, unaware of real threat around her, unaware of her 'childhood friend' lying her, which made her become less important than she should be.
This is my views, not from an AiCon but from a manga fan.