I definitely think it helps a film sometimes when there is a pool of unknowns in the mix in that it theoretically helps keep the immersion intact like Spirit mentioned. In this respect, I usually enjoy films more if the experiences is fresh, which is something a cast of lesser known actors can supplement well. I also would say that an actor's versatility is also an element in this equation. I recently saw Once Upon a Time in Hollywood, and that has a plethora of recognizable names; but their performances were entertaining enough where the experience was not dampened on the grounds of familiarity.
As far as animation is concerned, I think a lack of familiarity with the actors makes for a more pronounced experience in that sometimes voice actors act within their elements for the most part (more in respect to mainstream animated films, especially in the Dreamworks realm of things where their casts almost always consist of big-name celebrities). I enjoy Bee Movie for instance, but voices such as Jerry Seinfeld and John Goodman are extremely recognizable and can prove somewhat immersion-breaking as a result, even if the performances themselves are good.
Ultimately, I have not found that familiar performers have lessened my film experiences often, but I can see how familiarity can be problematic.