To start, we definitely don't want to landmark every lot, so the second suggestion isn't one we're likely to see.
Now, to your first suggestion. We know that Waze wants to eventually map every drivable area. That would include all parking lot lanes and may even include parking spaces, though I think the latter is going too far. Keep in mind that "eventually" could be years from now. Before that happens, they need to change how parking lot roads are displayed and that is something that's been suggested many times and I think is probably planned. Similar to what you said, the suggestion I always give is to show parking lot roads as center lines (you see a single line that would be in the center of the road/lane). That would be far less visible and should be fine even with every lane mapped. I also suggest that the visible distance for parking lot roads be reduced to whatever zoom level matches about 25mph so they don't show at all while driving most of the time, but will show up when you are driving slowly (you should be slow while in a parking lot). I'd also add that if you are ON a parking lot road and/or routing onto one within the next 1/4 mile or so, then it should show all parking lot roads regardless of speed. That will allow for cases where there is a main parking lot road through an area that has a higher speed limit and will also allow you to see the entrances to parking lots when you're getting close to a turn just in case you want to enter at a different entrance. We definitely want the parking lot roads to be visible at a certain zoom level because there are valid reasons to have them, especially in cases where you aren't in navigate mode.
And I don't know that many people care overly much about how it appears in the editor and we definitely don't want to limit access to those any more than they already are in the editor or we'll end up with people marking a parking lot road that is already marked, but can't be seen. That being said, I think there can be value in adding an option in the editor to not display parking lot roads (and optionally be able to choose what kinds of roads to display on a granular basis). This could possibly be done via plugin as well if Waze doesn't want to do it.