In my opinion [yours is allowed to differ. That is ok!]
2nd and perhaps of even more importance NEVER, NEVER, NEVER, NEVER, NEVER, EVER! even consider saving a Original and all Masters at less than the maximium size that came from the camera!!!!
There is never a reason to not save the original or master copy at anything less as you have just found out.
YES! there are reasons to use of send lessor qualities such as I did for my daughters ID badge for college or photos for online usage; however, the Original AND Master copies are [and should be] stored at FULL SIZE and quality.
PS: To me a master copy is the final rendition of the photo [after corrections] croping etc may have been done or may come later depending on its usage. It is possible to have the original and several masters of a photo as it is often that a photo may be used for several purposes framed, album, Newspaper and need handled differently for each].
For example lets say I have just shot a wedding: Almost all photos will get processed from RAW [mis-fires and other exceedingly poor photos or ones that could cause discomfort are culled immediately] to my work format, those that are not acceptable are then culled [removed]. those that remain will be corrected further and saved at full size [although there will be some that are also saved after being cropped] and some that are to be used for lets say a slide show that are saved full size and then reduced for the show. I may also do a few samples of other styles of photos [different finishes so the person ordering has an Idea such ad toned, B&W etc]and do not touch the master.
If the family purchases a cross-processed 20X30 inch photo for the livingroom I still have the Master photo ready if they want an 11X14" print for the grooms parents ...