I run into this all the time in ReportBuilder. My reports are gangly when I do not apply this type of filtering in Excel after running it. It seems that it would be a relatively simple feature to add.
This is especially important for discerning between iOS6 and other iOS's. When Apple removed the referrer in iOS6, we needed to use the OS version to estimate the amount of direct load traffic that is really organic search.
I find that I have to make changes almost every time I download. I know that they want to keep the initial default at 50, but it would be nice to be able to change that default by user. That would be a helpful compromise.
AND be able to schedule when it is emailed. It would be great. I'm also assuming that this would send a snapshot of the web page, not just the data, just to be clear.