A roadmap is a good idea, but it needs to be done right.
Frontier can't announce a detailed development plan with planetary landings in December 2015 and wings next week. Doing that would be just insane as they risk missing deadlines and over-promising.
From my experiencing, keeping to a deadline and to their promises is something FD are actually good at (offline mode is a very big exception and it probably wasn't handled very well, but that is a different discussion).
On the other hand, withholding information is generally a very bad idea. Every public relations officer in just about every military in the world can tell you that (just do some searches for military media blunders). In a connected world the military has had to learn how to handle media and control information in a setting where withholding all information is just not an option.
Traditionally Frontier has been a developer who has developed on behalf of publishers. This means that the publisher has handled support the public and marketing and FD has had a NDA in place for all involved.
Now they have entered a new arena as a publisher. On top of that, since ED is crowd founded, they have thousands of stakeholders who demand information on what is going on.
In this situation withholding information is not a good idea, but controlling it is essential.
Let's take slaving of drives as an example.
This was cancelled after FD took a closer look at the concept and decided that it wouldn't work as intended. The announcement caused a small uproar when it should have been cause for applause.
They looked at an idea and decided that it wouldn't work well and then came up with something they think is better. How can that be bad.
So rather than saying that "slaving of drives has been cancelled", one should say "the mechanics for players travelling together has been enhanced to work better. Slaving of drives where one player is allowed to control several ships was too limiting so we have decided to do it this way instead. We call it the Wings mechanics" or something along those lines.
So I applaud any general development road map from Frontier, but I don't want to see their internal development plan as that is probably subject to change on a weekly or even daily basis and would probably be more open to interpretation than EU regulations.