Reading direction should not matter. Creators spend hundreds, if not thousands, of hours generating free content for readers, with little to nothing in return. The least readers should do is be respectful and not knee-jerk judge a work or a creator's person based on the reading direction. Jerk reacting to one direction or another is much like seeing a person wearing glasses and deciding they aren't worth talking to just because they have glasses. Such kind of judgement is very myopic on the reader's part because fundamentally they are stereotyping another individual. How many people have experienced the bad habits of artists at conventions (condescending, judgemental, vain, etc.)? Well, readers can have bad habits too. As readers and/or creators, we owe it to one another to avoid such bad habits because all it does is reflect negatively upon ourselves as well as to outsiders looking in at the comic world.
Reading direction aside, what should really matter in a comic is the story. There's a saying in comics "if the art is great and the story sucks, then it's still bad". Ultimately an unpaid creator should get to decide which direction they want to tell their story and their reasons should be theirs alone. A creator should always feel free to express their ideas however they wish without fear of being judged. Unfortunately, once a creator starts to produce in anticipation of what readers want ("write for the market") they lose some of their passion and uniqueness. Too many compromises ("for the market") and too much passion loss and there is a very good chance the creator will abandon their work. Passion is often the only thing driving most webcomics.
However, in the defense of the stereotyping reader, perhaps some dissatisfied readers have read something written "in the wrong direction" and were disappointed with the series and felt cheated in some way (money, lost time, lack of realism, bad ending, etc.)? After several bad experiences with "the wrong direction", the bias develops in the mind of that reader where a particular direction is inherently flawed and should not be read. To them this is a valuable time saver since there are well over 10,000 series available on Tapastic alone. However they ultimately cheat themselves out of reading many good stories.
Additionally there are also some readers who will only read in a particular direction if the work comes from a particular region of the world. Otherwise that work is not "genuine". These hostile readers viewpoints cannot be changed. As creators should we really even worry ourselves with such gross negativity?
In summary, there are good stories and bad stories, both of which are written in either direction. Therefore direction should not matter, nor should the physical location of the creator. A work should stand instead upon many other merits. Consequently, if you are a creator asking which direction to write, maybe the critical question you should be asking yourself is, "am I writing for me or for someone else"?