Reading through all of the preceding comments the positions taken appear to view this as an either/or scenario.
A heavier download with more plugins included to get going faster (valid if that is where your knowledge levels are)
A lightweight download that is quicker to download so plugins can be mixed and matched and kept "tight" for your specific needs.
I suggest this does not have to be an either/or situation?
Here is another idea:
We already have platform specific distributions (Windows, Ubuntu/Debian, RedHat etc). Why not have a number of other distributions that include different sets of plugins.
These new distros should be IN ADDITION to the current available distros. The current distros should be as light as possible thus serving the demographic that don't want bloated Jenkins.
I see a download page that asks the user a series of questions (answers provided via dropdown lists) about how they want to use Jenkins.
Eg: What Source Control System do you wish Jenkins to use?, Do you have testing code? If so, what kind is it? What analysis do you wish Jenkins to perform on your code?, How do you wish to notify people of results?
The combination of answers would drive which sets of plugins get included in the distribution.
This would provide a starting point for the newbie user and should still be able to visit the update center to further customise/change their Jenkins as their knowledge increases.
I think this would be a major improvement and give people another way to access Jenkins.
What do people think of this proposal?