How often is always? I set it once and have never had to mess with it since.
Are you saying that Google should provide you with enough free storage to store all of your images at full res?
You know me, I'm a ROM flasher. I realize that's on me, but the fact the default option is full res is a bit annoying I suppose. Your average user won't know how fast that fills up, especially those in their 20s and 30s who are all about photos. I know people who go on vacations practically only with their smartphones.
Google doesn't have to offer free storage at all I know what you're saying, but the problem is this option makes it look so attractive like it's doing you a favor so you don't lose your photos. I can see the average user like OP's wife getting tricked and getting screwed somehow.
Running out of space on iCloud is less of an issue because you can clear your data and not be totally screwed. It's not that hard to clear out your Google/Gmail space. For example, ever since the full res change I've probably eaten up about 500mb. Those were from every once in a while when I ROM flash and I forget to turn the setting back to 2048x2048 (I don't do a clean wipe that often... maybe once every 2 months?). There's no way to easily go through your photos and figure out which ones were full res, nor can you change them to 2048x2048. It's too late by then.
Anyway, in the end it's not a big deal for me, but could Google make it more user friendly for the average Joe? Yeah I think so.