I only unlocked the Engi and Federation while playing without a particular aim. However, once I read the guide of how to get each ship I was able to unlock all of them but the Crystal and Slug in a few hours of gameplay. This is because you can be on the lookout for all of them at the same time while playing, and chances are you will stumble upon at least one quest for them and be prepared for the opportunity.
The problem is that for those who don't know the details, the combination of factors needed to unlock them is quite improbable. If you have no idea of how to unlock them, you have to be lucky enough to:
- Meet the system/crew requirement by chance (I'd say 35% chance in average)
- Go through the homeworld by chance (Chances of going through one without looking actively for them are of 30% per playthrough at the best)
- Know what options will actually unlock the ship (I'd say 25% chance to get it right in average, but that may be high considering that most ships are unlocked by a series
of correct choices*)
- Getting lucky enough to, once you finally find the sector and meet the requirements, find the actual quest (60% maybe).
All considered in this very very rough estimate, you would have 1,5% chance to unlock each ship each adventure (excluding the Engi and Fed).
*Let's admit it, quest choices/actions are not exactly intiutive. There is a mean rock cruiser blowing me up with missiles while a sun sets in fire my subsystems. I was actually supposed not
to blow them up?
And some ships, like Mantis, require very specific strategies that you may never use, in addition to
all the luck factors.
That said, I don't complain about the difficulty because I enjoy challanges, but only because I knew beforehand the details to avoid a whole life of blindly going through galaxies waiting to bump into a new ship by chance. I agree ships should not be unlocked at the start. However, hints to get the ships should be much more helpful. Remember that new ships are necessary additions to keep the game fresh, new players may get bored faster if they don't find them.