Re: AT&T Nokia 1520
So the utility of saving apps to the SD Card then sideloading them to the phone is that you can do it from your desktop and avoid data charges? Otherwise what's the point? Maybe it would be faster to sideload than to download directly to the phone? In cases when you wanted to install the same apps on a new phone. So you'd only incur data charges when updating (unless you went to the trouble of downloading updates to the SD and then sideloading).
I recall this same issue with Blackberry phones awhile back. There was some advancement IIRC and even some 3rd party programs that allowed running from SD. But that created a lot of performance issues, so having larger internal memory is much more preferable than being able to run off SD, although it might be some high-performance cards would allow decent results. By the time BB got up to 16g of internal memory, there was no issue. I never ran more than a few, usually small games, and also didn't mind the incentive to houseclean the device periodically, to cull out the apps I needed and used and to discard the rest. There are frequent OS leaks and upgrades with BB, so a lot of time and data was spent re-downloading apps which might have been helped if I stored them on the SD, particularly since backup and restore functions continue to be spotty.