Well having fewer colors allows them to reduce the costs.Back in the 90's Ibanez basses were NOT good; Now, Ibanez makes a really good product for the various price points, and having played quite a few bass brands over the years, I can honestly say that they are just about the best all around factory bass value wise. Playability and aesthetics are in the eye of the beholder.
That being said.....
They have a real problem with colors. Many of their color choices are, well, questionable. They also can't seem to understand that one boring or ugly color per model (in the higher ranges) does not cut it.
They do seem to understand the importance and beauty of tone woods, but then use too many on one bass or cover it in crap color.
They do not seem to understand that people do actually play 6 strings (many actually) yet do not offer many of them, especially fretless. No Steve Digiorgio 6? Really?
They had a great bass with the Single cut SRSC806. I have one and it's a beast! But they killed that model and never offered a 6 fretless.
I more than understand business and cost in manufacturing. But do they watch the aftermarket on their instruments? You would think a large corp like them would but I'm guessing they don't. They might learn a lot if they did.
Their aesthetic choices are varied. Some look awesome, some terrible - but at least they switch it up between years, so you get some variety
Furthermore a 6 string fretless? Assuming that 5% of all players play 6 String (and that is generous) and that 10% of those play fretless (which is generous as well), the market is maybe what 50 people in the US?