So, if I may put words in your mouth, what you would like to happen is the current behavior when a repeating project (or action group) is marked to repeat from the completion date, and have the repeat just magically appear the repeat interval after the previous one was assigned to start (regardless of completion status) in the case of a repeating project (or action group) marked to repeat from assignment date? That could certainly be implemented, probably without undue difficulty. It does make for something that behaves much differently in one situation than another (one repeats automatically, another you have to mark it for completion) which is one more little quirk for a user to have to keep in mind; in my opinion it is easier to remember rules that apply in all circumstances than having to remember a set of conditions for this, a different set for that, etc.
How many of these endlessly repeating daily items do you have? Are they all in one project, or many? One could fashion an Applescript to check them all for completion and mark them completed. Then you just need to remember to run the script when you're done for the day, or maybe trigger it from a nightly iCal event or something. Not as clean or convenient as a checkbox you can set in the preferences panel, but I usually find a workaround now to be much handier than a delivered feature in 6 months, at least for the next 6 months. Or in this case, just build the habit of marking the project complete when you finish it - maybe even put a reminder to do that in the name of the last action.
Here's another option. As you say, your project is never really complete. So don't complete it. Make it a parallel project with two items. First item is an action group containing all of the actions you want repeated (make the action group sequential). Set the action group to repeat at the appropriate interval (daily), based on assigned date. The other item is simply a reminder which tells you to mark the action group completed. Set it to start at such a time you'll still be looking at the program, but after you would have had time to knock off all the daily tasks. Set it to repeat at the same interval, also based on assigned date. For a little extra pizzazz, install the Growl notification stuff. In any case, after whatever amount of time you'd alloted yourself to get all the daily tasks done, the reminder pops up via Growl or just on your Next Actions list and you're reminded to tick off the action group, which immediately creates the next one, and then you tick off the reminder, which creates the next reminder.