No game is perfect. I'll draw attention to the huge income disparity in EvE Online. It's well known that if you really want to make money in EvE then you need to get in to trading and you shouldn't expect to be seeing that amount of income, or flying the kinds of ships you would be, had you gone down the trading route. On the flip side if you want to go out and be a pirate or get stuck in to the zero security politics and generally spend your time doing less income related things, you really shouldn't be expecting to be making an equivalent income.
How does Eve balance this though? Well you have the ability for multiple characters, and it takes a long time to 'develop' a character into the skill set it needs to master that character's profession. You can also find loops around the game systems to transfer money from one character to another, enabling you to effectively balance out your different game needs, enabling you to be completely self sufficient given a large enough time investment.
Although ED might feel like it isn't balanced, I think it's a problem that people seem to want an equivalent income across professions, when they by nature would have a large disparity anyway. I think the real problem is that we only have one character, and we also have the ability to play across professions as and when we want to. There isn't a vertical progression to any of the professions that requires a time investment that feeds round into more advanced and increased rewards for committing to that time investment. I feel it is like this because we have one character, and so the game design is balanced around the individual's ability to 'blaze their own trail' while being limited to a single character.
How do you create vertical progression [increasing returns] in a system that is so 'open' that it caters to anyone doing any number of things in any combination they chose to at any time? I don't think it's possible. So it seems FD have essentially created two competing gameplay philosophies that currently lack the mechanical content to bridge the gap between them.
More specifically, the reason we feel like we need balance across professions, isn't because there is a problem with balance per-say. It is because there isn't enough vertical depth to each profession and over all mechanics that allows bridging between our chosen establishments within those vertical choices. My example being the multiple characters and asset transferal available in eve, with enough tertiary content (meta game) along side that to allow a healthy gameplay loop to emerge.
As it stands in ED, we have a system that is by design too 'open ended', too laterally broad and not vertically deep enough, to allow for any proper player investment in any one profession except for in the case of income, which is what makes us think it's a balance [income] problem. My argument is that it isn't, the problem is a deeper, more mechanical one.
FD shouldn't focus on balancing credits/ph, they need to work on making the professions deeper and more long term, more "realistic" and believable; and once that has been done, we as a community will not be so focused on credits as a focus of gameplay. We will by then have enough to become invested in in a proper gameplay sense. Making this "they need to balance income" hopefully calm down a lot. I think a lot of us are maybe missing the point a little bit, it's a subtler point sure, but to me it's the cause of a lot of this current debate.