Is windshield trim necessary?

I would add the trim if it was me, I put my windshield in with 69 stuff and didn't add the trim for a bit. It has about a 1/4-3/8 gap on all edges.. It doesn't look horrible but it's obvious it's not complete. Not sure if you can tell, but here is the best PiC I have

Hmm, I think I can get a reasonable idea from that. Mine has a bit of a gap already because a large portion of my lock strip is missing and the gasket is pretty dry and starting to curl a bit. I think it's actually leaking between the window and the gasket, not the gasket and the frame based on the way it was dripping this morning. The gasket actually looks dry on the inside, even when I can see water dripping. I'd try just getting new lock strip to fix it, but that gasket looks pretty weathered to me and if I'm going to have to pull the windshield anyway I'd rather just put something new and fresh in.