Well, because I’m unsatisfied with those I’ve tried. I’ve tried a bunch on Linux and Android (I’m not really that much of a Windows user although I’m dual booting and using it at work; I’m not at all a Mac user) and all have left me wanting. The first step in my quest of a vector graphic program will be a review of a few program and what I don’t like about them.
But first, let’s look at what I’m looking for. Because I’m convinced that the reason for which I’m unsatisfied is that my goals aren’t those of the designers of the programs I’ve tried.
I tend to classify vector graphic editors in three categories depending on their end goal:
drawing scalable images;
designing special purpose diagrams such as flow charts, organigrams, UML diagrams; their use model is specialized for the kind of diagrams they support, but outside of their target applications where they can be very convenient, they are limited;
drawing general purpose structured graphics; they don’t want to be as specialized as the second class because that specialization brings its own limitations however convenient and even indispensable they may be for heavy users, but want to be usable in more contexts for the same generic kinds of graphics.
My goals is the third category. What features do I want?
snapping to a grid. The fact that this feature not on by default is a good indicator that the program is for the first category. Even more if it is absent or difficult;
user definable symbols; the first category usually don’t have symbols; the second category is build over symbols and connectors between the symbols, but often give them too much meaning and do not allow the user to use anything outside their built-in libraries and give to the symbols the special capabilities which are at the core of what make them special purpose;
reference point for the user definable symbols; the snapping on the grid of such symbol should not use the bounding box of the symbol but a user controlled reference point which allows to ensure than some other features are on the grid if the grid steps of the symbol and the drawing are matching. Bonus point if there is a way to adjust the symbol to make them match;
connector targets in user definable symbols;
easy placement of texts relative to drawings; aligning the middle of the x height of a text to a line is a must have for me (think about labels for the previous point connectors; depending on the font the middle of the bounding box may be acceptable substitutes but the editor should not force to use such work around);
lines which stay connected when moving other objects; ideally that should not be restricted to symbols; that should not be restricted to a single Z shape; the connector targets should not the restricted to extreme or center positions.