Unless you download once a month or you have a very large transaction load, I don't see how this is an inconvenience.
If you download infrequently, maybe you might want to change that to a more frequent schedule.
The feature I suggest is useful in two circumstances that I have encountered: I have one bank that only releases transactions at the time of billing (approximately once a month). I have bugged them about that, but that is the way it is for now. So that is one of the circumstances.
The other circumstance is when running Quickn on a tablet with a small screen. Even a couple days worth of transactions can be "long" in that environment.
In the Downloaded Transactions tab area, have you noticed the "Hide Accepted" button?
From Quicken Help:
Click the Hide Accepted button to remove transactions from downloaded transactions list as they are accepted into your register. This helps with readability. After clicking the button, its name changes to Show Accepted, which you can click again to restore the transactions to the list, if necessary.
That button does exactly what you are suggesting.
So the Accept button accepts just the highlighted transaction? and Accept All accepts everything that's been down loaded? If that's the case, I'm with Glenn. If I accept all but 2 transactions because I need to research them, I'd rather they not be moved out of Downloaded Transactions tab until I'm ready.