In my experience, quite a few people say such things elsewhere as well, but if you actually give them the opportunity to do so (even if it's not "a lot", but actually a pretty small fee), such offers tend to perform badly, even among the people who initially requested such a tier, unless ads are very, very intrusive (Youtube of late might be such a case) or it's bundled with other, actually useful functionality, more content etc., or rolled out as an increase of existing pricing instead of a separate offer people have to actively pick (risky in itself).
People in general appear to be much more price-conscious when it comes to such things than they themselves seem to realize.