Have parent-project appear in daily to-do list and/or enable project priority inheritance
Enabling project priority as a feature would influence the order in which tasks are displayed in the to-do list. That be very useful for the ones of us that need self-control in attacking their to-do lists, and are easily swept away by all the small tasks they need to do before getting to the really important projects.
If the parent project would appear on the daily list with the possibility of hiding all the tasks under it that would allow for more control of work flow, and better focus on the important projects, not on the urgent ones.
On a personal note:
At the moment I am trying to get more productive by separating my projects in three main meta-projects/types of work.
One involves mosquito tasks - things that appear day by day and one has to do, that only take a few minute to complete but have the habit of becoming urgent or very distracting if I don't have them all in the same place.
The second involves work obligations projects - stuff that I need to do whether I want to or not, that normally takes priority by the simple fact that it has to happen at certain point in time, and it involves preparation beforehand (and feelings of social pressure and inadequacy if one fails to prepare).
What I am really trying to make time for is the third type of meta-project, which involves the real creative work - something that I need to book uninterrupted time for, and it comes with its own lists of sub-projects and tasks. As the mosquito tasks have the advantage of urgency and the obligation project the advantage of dedicated time slots, introducing uninterrupted quiet creative time when I can actually think and research and develop my ideas can be quite a challenge.
But if I could only hide the mosquito tasks and obligation tasks under their meta-project - as at the moment kind of gather in a bit mess on my daily to do list - then I could really have more focus on the creative tasks, which are the real priority in terms of importance and future benefits.
I could of course take the time to rearrange my daily list - but this takes too long, or just color code or add priorities to absolutely everything - but this takes too long again when it's done task by task. So if only my tasks would inherit priority (which decides order on to-do list) and/or color coding from their parent projects and meta-projects, my list would be so much easier to navigate, and I could really work on it in a GTD style, of picking one item and solving it, then moving to the next one.
It is worth mentioning that I would also do this prioritizing with labels if it would be possible to add labels to actual projects.