Let's step back from the details of the question for a sec…
What you can learn from someone checking out your profile is simply that their account is active, nothing more. If nothing else, this should say to you that they are worth writing to, if you are interested.
Don't overanalyze things. If you write and get no reply from someone who did check your profile, you have exactly the same amount of data about their interest level as someone who hasn't seen your profile and doesn't reply to your message.
Given all the other reasons they may not have messaged you (many sites only let paying members send messages, for example), it's in your best interest to pursue everyone you take a fancy to when you're searching online, so long as you take your time, and make a proper effort.
To be perfectly clear: I don't think that "who's viewed me" is a useless metric, but I think that it shouldn't carry much. I also don't think that "never viewed me" users are more likely to be interested.
In the end, I'm just concerned that the querent might spend so much time trying to find someone "likely to be interested", that they forget to BE INTERESTING, and to PURSUE PEOPLE THEY ARE INTERESTED IN. 🙂
If you know that someone has visited your dating profile and not sent you a message, is it better to contact them or to explore other matches?