I'm sure you can do many kinds of therapy and have it be helpful in any number of different ways. But if you're in it for any kind of longer haul... Well, it seems like not talking about the relationship becomes avoiding talking about what is likely to be a very significant part of your life. How you feel about therapy, how you react to your therapist, how much trust you have in her --all those things are important because they give you a lot of information about how you are in relationships in general. Your ability to point out vulnerabilities and misattunements is key to the success of your therapy, otherwise how can your therapist be optimally helpful? And how can you do that without talking about the relationship?
For me, the relationship itself, the calm and accepting demeanour of my T, have been at least as important to my healing as any of the topics we've addressed.

If the T is ignoring those elements or not facilitating that discussion what is the client supposed to make of that silence? It could be awkward after awhile, no? I think the T checking in about that gives you permission to explore your feelings about them, about the therapeutic process and about your feelings in general. Without that element, IMHO, you're missing out on the depth and richness of the experience.