Melissa, Moodle is an Open Source product with a vision, a strategy, a roadmap and a team with Martin as lead developer. This team takes care that development stays on the roadmap - besides all development work.
Martín Langhoff described a very important aspect about Moodle development which is not on the main Roadmap. You need to prove that your idea is working, either by proving with code or with arguments that convince the core team.
On both ways I too was able to successfully contribute to the Moodle development:
With good arguments and layout scribbles I could show how a possible change of the XHTML hooks and CSS system might work. It has been implemented in Moodle 1.5.
Besides arguing for Ajax and an JavaScript interface library I was showing a working Drag&Drop course and proposed a project for Google "Sommer of Code". In Moodle 1.7 a JavaScript library and the Drag&Drop course will be implemented. You may search the forums and will find several postings where people stated that Ajax is not important for Moodle. They spoke for that time and the needs evolved.
A very important benefit of this sometimes hard and in some cases frustrating procedure is that you do not only need a good idea but you also need to have good arguments or examples why this idea is important. And while discussing your idea you will see if it finds consensus. If not you will either see that the idea can't work or you will find new arguments, other point of views etc. to bring the discussion forward.
Keeping a complex software on a good way needs a strong protecting power. I suppose one of the reasons why Moodle is successful is this power. In most comparisons about CMS systems I read concerns about the reliability of Joomla! development because of the strange branching from Mambo. An everything goes strategy does not lead to a successful product.
Bring in your ideas, prove that they work and be successful with Moodle. If Moodle might not be the right product to work the way you want please be fair and choose another product without blaming the Moodle core team.
Urs