yeah dude courthouse weddings are a thing. if your only real objection to it is that you don't wanna blow money on it, then you're just not looking at all the options. Also, damn dude, she's said she's fine with a small wedding and youre still this hesitant on it? cold, bro.
you can get a lot of similar protections for your spouse individually but it's difficult and time consuming and often leaves room for legal issues if something should happen, whereas marriage is clearly defined and relatively easy. example: you're on your deathbed, she walks into the hospital and says "I am rata's designated bullshit legal term here, let me see him." they're gonna need all sorts of verification before they let her anywhere near you. She says "I am Rata's wife." and they MIGHT check her ID.
It sounds to me that you simply don't really care either way aside from the financial aspect, so look at it this way: If you don't feel strongly about it, it's important to her, it would protect you both if something happened, AND you can find a compromise on the financial issue, why the hell WOULDN'T you get married?
I have a buddy who thinks the way you do and honestly I don't get it. The only objection either of you seem to raise is that it's "wasteful" which okay fine but you can literally just pop into a courthouse and sign some papers and be done. You MIGHT need to bring some witnesses, but they usually have notaries around so even that I think wouldn't be insurmountable. How wasteful you want to be about that process is entirely up to you and your SO.