I'm going to get straight to the point: YES. A thousand times, yes.
But, don't you worry, if you're a little on the fence- I got you! I wrote up 5 major reasons you should hire a photographer.
4 Reasons Why You Should Hire a Photographer for Your Proposal
#1 Our gear (and skills) works better than your friend's phone.
Sigh. I feel like I shouldn't have to make the argument at this point, but, alas, here I am again. I'll keep it simple: Your friend's shakey cell phone pics just wont do it. And no, Portrait Mode does not make up for that.
My old photo boss used to always say "It's not the arrow, it's the Indian." This goes both ways, it does not matter how fancy (or simple) a camera is, it does not automatically make you a good photographer. You're friend might have a cool instagram profile, but if they don't know about lighting, timing, and settings, then they honestly might f this all up. And your proposal is a moment you don't want them missing the mark on.
I'll touch more on this later, but remember that hiring a pro means we've built the experience so you don't have to worry about your moments being held on a shakey cam.
#2 You can't remember the moment for all that it is... not really
Here's the spiel: Big moments matter so much to you in your life, having a photo -or several- you can look back on will take you straight back to that moment.