Wow, I was just talking to a buddy about this very same thing. For starters, I think it's largely of low value. But for some guys, there might be some value (but still not a lot). My son is one of those guys (I think?).
My son came up short of his D1 goal and is going the Juco route this fall. In that respect, his recruiting process will not be fully complete until he lands at his final college destination. He's maintaining regular contact with his D1 targets. Keeping them updated and working to stay on their radar. As if to say "Hey, I told you I wouldn't quit and I'm not. You haven't heard the last from me." He'll be playing the relentless/tenacity card until he reaches the school where he'll complete his degree. So doing a showcase and performing well creates a reason for a touch point with his 4-year program targets, but also an opportunity to show progress. Progress is one way to show projectability and projectability is king, right?
There is also an undeniable "branding" piece to the whole recruiting process. Nothing attracts a crowd like a crowd. Any time you can attract a crowd, I'd argue it's worth it. We all know how EVERYONE talks. The college baseball community has like 1-2 degrees of separation across the country. If you're not done yet, you want to keep your name/brand relevant and visible. You're always building your brand.
My 2 cents (and my written way to substantiate me spending money on low value things. )