Receiving thanks from the poster, it seems to me, puts you in the position of participating in an ongoing conversation, if you choose to follow up with a hint about how answer acceptance works at Stack Exchange sites. And as long as your answer isn't the only response to, say, a two-hour-old question, I don't think such a comment subverts EL&U's preference that answers remain unaccepted for a decent interval in case a better answer comes along within a reasonable time.
Initiating a conversation along the same lines when the poster hasn't said anything to indicate appreciation for your answer strikes me as falling closer to the line of soliciting for points. I've seen answerers do it, and I don't think it's impolite, exactly, but the self-interest quotient seems higher.
Some long-time participants at EL&U have occasionally expressed frustration at the tendency of first-time question askers not to accept answers that thoroughly resolve their question. To those observers, it is the questioners who exhibit bad manners, by not acknowledging the usefulness of the answer and the effort that the answerer made on their behalf. And since very-low-rep askers don't have the power to upvote answers, the only ways they can express gratitude are by posting a comment of thanks, by accepting an answer, or both.
Even so, asking for green check marks seems a bit unwholesome. If the goal is to introduce new questioners to the etiquette of answer acceptance, the selfless thing to do (which you and some other site participants have done) is to leave comments on questions where you don't have an answer in play, pointing out the acceptance option and suggesting that using it is a good way to indicate satisfaction with an answer. It's a public-spirited approach, certainly—but no one wants to spend all day monitoring the board for seemingly ungrateful first-time questioners.
Ultimately, answering an interesting question well is its own reward; and the more fully you believe that proposition, the more fun you'll have here.