Part of the issue with tarot is the humanistic approach that has been piled onto the cards. It has become all about feelings and psychology. A skilled reader can use tarot cards with the same pin point accuracy to foretell specific events as with the LeNormand cards. It has to do with one's approach to them.
I agree. You can read any deck in any way you want, but what do you hope to get from those cards?
Are there better and not so good ways to get the kinds of responses you are wanting or needing? Is one deck better suited for a certain kind of information or technique than another?
For instance, some European cartomancy decks feature a lot of cards having to do with love and marriage - far more than the other decks. Some decks feature types of people - old, young, widowed, wealthy, poor, military types, professionals, thieves. They are like the folk rhymes and counting games that are supposed to predict who a girl will marry: "Rich Man, Poor Man, Beggar Man, Thief, Doctor, Lawyer, Indian Chief."
http://en.wikipedia.org/wiki/Tinker,_Tailor .
We need tools that suit our proclivities (natural talents and ideals) and ones that work best with the kinds of information we want. Some decks can serve a variety of options, while others are more limited.
Tarot is incredibly flexible and was not created for fortune-telling. Rather a number of very different ways of reading the Tarot were developed and perfected hundreds of years later.
Leormand, in even its pre-Lenormand forms, was created for fortune-telling and the core meanings have been part of it since the beginning (with very little variation until recently). Does that mean it shouldn't evolve? No - I don't think we could stop it, but I think the approaches that take the Lenormand strengths and inherent unity into consideration will be those that last the longest.