I'll take a stab at this. I think sometimes the feelings of attachment become the elephant in the room, and it gets hard to talk about anything else until it's been brought out into the open.

With good T's, I also think it can alleviate any feelings of shame or worries about inappropriateness of feelings, especially for clients who are less familiar with transference and don't understand how natural and common it is. Or who don't understand how unmet needs from childhood come to the surface in therapy, so of course we have child-like feelings sometimes.

And then, it could lead to discussions about those unmet needs that are feeding into the transference. I talked to my T about my clingy, childish feelings and he helped identify that I had not had a trusted adult to talk to about the bad things going on in my life at certain ages. This was true because I hid so much from my parents, but I did have loving parents, so I would not have expected to have this transference. It was useful to talk about it and see that I had indeed had a need that had not been met at the time -- though I don't blame anyone for this, it just happened.

And lastly I think that discussing most emotions can help lessen their intensity, and clients really suffer with transference sometimes, so that's quite necessary to make therapy tolerable for some of us.